3-Reel Standard Slots - these are the most usual slot machines. You bet a certain amount, then spin the three reels and depending on the outcome of the spin, you either win or lose.
3-Reel Max Bet 2 Slots - these machines allow you to bet the maximum of two coins, not three as in Standard Slots.
Progressive Jackpot - a progressive jackpot means that a certain percentage of every bet goes into the progressive jackpot pool. You win the jackpot by obtaining a very high symbol combination, usually only when playing for maximum bet.
Bonus Game machines - have a Bonus Game require you to obtain a special symbol combination, or collect certain symbols. When you do, you will enter a bonus round, with special prizes waiting for you. Please note that in some games you have to play for maximum bet to qualify for a bonus round.
3-Line and 5-Line Slot Machines - here you specify your bet per payline, and the paylines on which you bet. A payline is the line along which Your total bet is then line bet x number of lines selected. 3-Line Slots have 3 lines for you to choose between, and 5-Line slots have 5.
Multiline Slots - same as above, only these machines have more than 5 lines, usually 8 or 9.
3-Row and 5-Row Multispin Slots - after the first spin you choose which reels you want to hold, then spin the rest of the reels again. 3-row and 5-row mean you have 3 or 5 rows of reels.