in mta there are mainly two different servers..
1 is stunt (you do mono's flips whatever to gain money, money = points)
2 is deathmatch (gangs vs eachother, start with weapons etc)
Both you get to choose from a viarity of gangs, for instants.. theres the chef's which start at the airport, theres the prozzie's which start at the hospital etc. Its good but I dont know what the community is like anymore, mta kinda died out when san andreas came out.
However, there s now MTA:SA or aka crappy mta race, not sure if people still use it, I myself use SA:MP which is absolutly great, HUGE HUGE community, tons of different user-made game modes, up to 100 people in 1 server.. You get to choose your character at the start.
The main game mode in SAMP is "venturaz land grab" or "money grab" land grab its like a hold the fort type game, you go to the ship in venturaz and hold it to gain money, other people can team up with you.. you can buy stores to gain more money, you can bank money so you dont lose it when you die (you lose it when you leave the server tho).. Moneygrab you go and gamble to make money.
In every game mode of samp you are able to go and do up a car, fly planes/boats/heli's, swim.. you know all that good stuff.
You buy food to regen health, go to ammunation for guns and armour.
if you have san andreas or can get your hands on it... its well worth it.. any version will work online but main support is for v1.00
hope this helps