Anyway back to the main topic at hand here, I did write a reddit post for a basic comparison, but I would like to go into more detail here. Before that, it would be nice to give some context into this comparison. There is a few posts questioning why LOL does not have as big of a prize pool as DotA2 (TI5 had the largest prize pool in esports history), and a viewership fewer than DotA2(comparing between 2014 internationals and 2014 season for LOL).
LOL does boast the most time spent on it in 2015, but it does not provide any boost to its current value. Value is given by the players, and the players have said otherwise. The same could be same for some other MOBAs attempting to recreate DotA2's success, and failing in the process.
While I could not deny that LOL is much newbie-friendly than DotA2, considering its forgiving mechanics, and playstyle, DotA2 is a game that undeniably requires more knowledge considering its advanced mechanics and larger scale of gameplay, which IMO is brought in by the fact that you can alter the landscape of the map, among other things.
Other MOBAs such as strife and paragon, which tries to emulate the way LOL is played and advertised, emphasizing constant combat, and personalized user accounts, falls into the same trap as LOL had been. Players have been saying that LOL has grown stale, and that it does not have much variety in its playstyle. While you can see a lot of strange strategies come and go and win in DotA2, like an aggro trilane, dual mid, dual roam, 5-man at minute 10 strategies, LOL games typically only have a few set strategies, some of which is similar to DotA2, but cannot be executed well because of differences in the map and mechanics.
With our eyes set for TI6 prizepool to overtake TI5, one may wonder what is the difference between these two games that really makes the cut. Many posts such as this and this and this tries to look into the differences, but most of it is done by players who have less experience in DotA2. Due to the difficulty in DotA2, spending even number of hours in both games does not equate.
1. Heroes are all free in DotA2 while LOL's champions are not : This affects gameplay in the way of information. As players may attest, you can't just watch and read a skill description to understand a skill. Most of the time we learn by experience. DotA2 allows you to go into bot games and try out all the heroes and find your niche. Perhaps you would prefer playing heroes that push well, or heroes that does skill shots, etc. However in LOL, you start out with a limited hero pool, all of which may not suit your play style. You're boxed into thinking these are the heroes that are "for noobs", when in fact there are champions in there that are constantly banned or picked only in high elos due to their specific playstyle.
The result of this is that casual gamers, who watches a game of professional DotA2 could at least understand what's happening on the screen (with the help of casters of course) and try it out in their next game of DotA2, adding to the excitement and changing the meta itself. For casual LOL players, unless you've unlocked those heroes, it is unlikely that you can do that.
2. Runes and masteries in LOL : A person with lower hours played, but with sufficient experience in similar MOBAs such as HoN, can quickly get up to date in DotA2, but they can't do so in LOL, as they would be lacking of runes and masteries, resulting in uneven gameplay. Gameplay is rewarding when you win against a tougher opponent with your skill. That, as with above, is why some professional play in LOL may fail to be executed for casual LOL players even though they did the philosophy right, which is disappointing for players.
3. DotA2 heroes are much much versatile than LOL's champions : You can play a mid antimage or carry warlock if you wish (as OG.Miracle- has done) and it will still work. LOL's champions have much lesser flexibilty in their game play, and their spells feel a bit generic even though they have their differences. There is no clear line between who does what in DotA2, and while this may be confusing for newbies, it provides much more variety when it comes to gameplay.
The reason why gamers continue to return and play a game is the variety it has in the game. LOL lacks the particular variety for casual gamers unless you play a whole lot and unlock heroes. DotA2 provides this variety straight from the start.
4. DotA2 maps are much bigger in scale than LOL, and it can be interacted with the characters : Some of the first few things people notice, coming from League is that you can cut down trees in DotA2! LOL has its landscape set in stone, and this, again reduces variety in strategies, and teamfights. However, LOL has special neutrals that provides buffs when killed, which is very important in teamfights. Meanwhile in DotA2, neutrals provide skills that you can use once you control them.
In DotA2, the jungle is a resource, and efficient carries often find ways to exploit map stacking and pathing and tree cutting, but in LOL, the jungle normally would be reserved for the jungler alone, and farming the jungle is much slower than in DotA2, without the before mentioned mechanics.
5. There is really no way you can alter the creep equilibrium in LOL, unlike in DotA2: Without deny mechanics and pulling, the carry often has no way to keep out the enemy offlaner from getting exp, or keep the equilibrium at a safe place to farm. This keeps the laning phase from growing into a stale farm game, and encourage aggression from both sides in LOL. Which also means that carries with low early aggression potential early game, if paired with a high aggression enemy would likely lose the lane. Also, this means that it is hard to close the experience gap once you've been ganked once or twice since there is really not much safe lanes to farm.
6. There are no TPs in LOL : TP scrolls, IMO, is the most important item in DotA2. It allows you to channel a teleport to any allied building, but comes at a cost of 75 gold. Also, any allied TP within 20 seconds will add 1 second to your channeling. Everyone will buy it. It provides defensive and offensive uses depending on how you use it. However, the closest thing we have in LOL is Recall and Teleport. The former channels for 8 seconds and is broken on any enemy damage while the latter has a 4+ minute cooldown. Ask any DotA2 Player and they will tell you that an extra second in channeling that TP already feels like an eternity.
In DotA2, supports tend to TP to a lane to help a ganked ally. In LOL, only supports with the teleport spell can do that, and once its baited, it means that the support can't help another lane for 4 minutes. Not only that, it is important to TP to a rosh fight to prevent the other team from securing the aegis. So, controlling the towers and gaining map control is an important factor in winning the game. In LOL, it doesn't really matter if your tower is gone, since it doesn't provide any tangible advantage to your team. There is a lesser emphasis on controlling towers in LOL. In DotA2, towers are also important to protect your own jungle, but this control is also diminished in LOL. Basically if you are ganked anywhere in LOL, you can't really expect your supports to TP if they have used up their teleport.
This also affects heroes with innate tower-pushing abilities, like Ashe. Her Q does wonders to towers, and if it was introduced to DotA2, would be nerfed within a patch. Her E scouts brilliantly, like Clockwerk's rocket. However, her skill set does not match the requirement's of LOL. She, like her DotA2 counterpart, Drow Ranger, excels in splitpushing, but due to the way LOL is played, she is rarely seen past lower ELOs, until the very High ELOs, because she lacks an escape, contributes quite less to teamfights without items (which means she has to solo farm), unlike Drow, who has a silence knock-back spell.
7. There is no death cost in LOL : In DotA2, we often expect death number to be correlated to their position. Pos1, often carries, die the least while Pos5, often supports die the most. The reason is that most of the time, Pos5s have to sacrifice themselves to save carries, like slowing or stunning the enemy to allow the carry to escape. This results in supports carrying less gold, and thus their items comes online way slower than in League. Supports in DotA2 often have to spend money on cheap escape or mobility items to reduce their deaths and increase their contribution.
In LOL however, there is no death cost, so really this encourages offensive play from both sides. In DotA2, people are hesitant to dive, or play aggressively as TPs from supports may come (from the first point) and they may die, thus losing gold they get from CS-ing, which is a waste of time. In LOL, you don't want to die to feed the other side, but the reduced penalty causes a larger tendency to fight all the time. This, coupled with the next point, is why Junglers are a must in LOL gameplay, which is basically if you play DotA2 by ganking all the time.
8. It's really hard to have no mana in LOL : The only thing limiting you from using your spells, is possibly your cooldowns. Basically you're expected to keep spamming your spells to harass the enemy. In DotA2, this is mainly done by the supports in the lane. However, the reason why carries are carries is because their spells are supposed to scale with their auto attacks, and are supposed to augment their auto attacks. Meanwhile, supports have utility spells that can do CC. This means that carries have spells that are weak early game, and in a dual lane scenario, are extremely disadvantaged. It also means that pushes can be done continuously as the only limiting factor is cooldowns and health.
9. There is no buyback in LOL : DotA2 has a mechanism to cheat death by buying your way through. This rewards teams with a high gold deposit, but was picked off or something so they can still defend with the team. In LOL, this results in Aces, or Team wipes, and just end the game, unlike in DotA, where you have to be cautious of their buybacks.
10. Stuns in LOL last shorter than in DotA2: While this reduces being "stunlocked", it also takes away another comeback mechanic for teams in LOL. In exciting games, people often talked about games where a team manages to comeback through the use of continuous stuns in DotA2, like the way NaVi won TI1, while in LOL, often the winner just snowballs into victory and it's hard to actually comeback with a huge deficit in LOL.
In a conclusion, there are many advanced mechanics that makes DotA2 a much rewarding game to learn and play unlike LOL. This affects viewership as it makes game play much exciting to watch due to the variety of strategies involved. I believe this is also one of the reasons why DotA2 is growing in the international esports scene compared to LOL, in spite of clinching the Korean esports scene.
