Many bar leagues are poker leagues where people win points and have cumulative leaderboards over the course of a season. This is nice because you can have fun playing game-by-game, but also have fun by possibly winning a prize at the end of the season. Some bar leagues may have a large prize, such as a seat to the WSOP. With bar leagues, you will probably be playing against the same players over and over. This makes it a little more interesting if you want to improve your game because you can create profiles of different players (good vs. bad, etc.). Since there will be the same players, it will also be the kind of environment where you will make more social connections compared to a one-time charity tournament. You usually won't have to worry about the game being busted. The hosts have usually received permission to host the game.
These games are tournament where the host of the game raises money for a charitable cause by taking a portion of the total proceeds of the tournament buy-in. Most of the time the charity will be a church or fire department and the tournament may be held at a public place like the VFW. Usually the share that goes toward the charity is only about 20-30%. This is high enough for the charity to make some money, but low enough for a player to win a large amount if they do well. There are occasional games where the charity keeps a huge portion of the money (like 80%). These games are basically rip-offs and you shouldn't play in them. If someone wants you to donate money then they should just ask you instead of hosting a rip-off tournament. These are also games where you don't have to worry about the games being busted, although it does occasionally happen.
These are your typical home poker games where someone hosts a poker game at their house. These games may or may not be illegal (depending on state law) and have a decent chance of being busted by police IF they are discovered. But these games (in my opinion) actually have the lowest "bust rate" because they are usually advertised discretely.
These are illegal underground poker games that are run the same similar to legitimate casino poker games. Many times, they may have dealers and waitresses. They rake their games and are run for-profit. These games are almost always explicitly illegal and would certainly be busted eventually or get broken up or moved.
A couple of random notes. Because bar leagues and charity games (where the players are less likely to know each other) are more social events, etiquette is more relevant. The level of skill at these all of these games can vary widely between all of these types of games.
HPG ADMIN on March 1, 2013