Dota is not a MOBA.

Basic terminology:

Dota 2 is officially an "ARTS", not a "MOBA". "Creep", not "Minion" "Hero", not "Champion" "Tower", not "Turret" "Barracks", not "Inhibitor" "Roshan", not "Baron" or "Nashor" "Ancient", not "Nexus" (Sometimes called throne, a term from WC3) "MMR", not "ELO".

One thing to understand is that Dota is not a MOBA. DotA was made in the RTS game Warcraft III, and since Dota is basically a modified RTS game, the genre was specifically based on the genre of the original game, thus making it an ARTS. The term ARTS was used LONG before the term MOBA was even heard of, but rarely used as Dota was the only game of its kind.

Also, keep in mind that your rank in LoL does NOT matter when you're playing Dota 2, your League habits should NOT apply to Dota 2 and be open for anything. There is more than just one way to play the game with your forced META, year after year, which tells you to play in a certain way or go to a certain lane. Many, almost all heroes, can be played in different ways. Called "support" or "carry" doesn't always mean you're playing a support or carry-only hero. Carries can be played a supports and supports can be played as carries. For instance; Naga Siren. Picked every now and then to be played as a carry, but other times as a support. This, of course, applies only if you know what you are doing.

• Every hero is available for everyone, though some heroes are a lot harder than others.
• You have a courier that can bring you items and is a BIG deal in Dota 2. (My LoL friend, for some reason, cannot understand why the courier exists and why it's a good thing to have).
• There are runes that spawn every two minutes, haste, double-damage, illusion regeneration and bounty.
• You can deny your own creeps (and heroes!). Creeps can be denied at <50% health to reduce the EXP the enemy gets and potential gold. Heroes can be denied at <25% health if they have certain damage over time spells on them. Towers can be denied at <10% health to reduce the gold the enemy gets.
• Microing is a term in Dota which means you can select multiple units. You may think it's like playing LeBlanc or Shaco with her passive and his ultimate, but you are ENTIRELY wrong. You can select and deselect multiple units, including your own hero, unlike in LoL where your "champion" is always selected.
• All units have a turn rate, this will feel like lag during your first games, but it'll get better.
• Items can be dropped, stashed and sometimes shared to other players.
• You will lose a portion of your gold when you die.
• You cannot spam your abilities like in LoL. Mana management is VERY important.

There's tower aggro, closest enemy unit or hero attacking a friendly unit with auto attacking takes the aggro priority from the tower.

We also have day & night cycle, game starts at 00:00 in-game, which is day time, but prior to that, it cycles. Every 4 minutes in-game, the time changes. First night is essentially at the 4 minute mark. The game time affects the hero, creep and building vision. Some heroes have regular 1800 day vision and 800 night vision, though some heroes have exceptions. There is also a new item called the "Moon Shard" which gives you +250 night vision.

I recommend reading Purge's guide "Welcome to Dota 2, You Suck" and of course watching gameplay videos. Don't be afraid of going into the game playing for the first time, we've all been there, though I would imagine a lot of smurfs and other players getting pissed off because you might (let's be honest, you WILL) suck.

Also, once you realize Dota isn't too bad, you'll feel a lot better about yourself knowing you are playing the superior game. Good luck.