JohnnySlot,

I believe single coin slots means that no matter how many coins you play, the payout is the same odds. For example, the next time you go to the casino, noticed the DOUBLE DIAMOND machine by IGT and its payout menu. If you play one coin and hit DOUBLE DOUBLE DOUBLE, you will get 800 coins. If you played two coins, you will get 1600 coins. That means you get 800 coins for every coin played. Therefore you are not penalized for not playing max bet. Sometimes on 3 coin versions, you will get paid 2500 coins. The extra 100 coins is an incentive to play max bet as well as it can lower the house advantage. But besides the 3 double symbols, the 3 coin version's payout for 7's and bars are the same for every coin played.

MultiCoin slots are what they consider "buy a pay" and progressives along with some others. Why? well, for example Blazing 7's machines are buy-a-pays. If you notice, the first coin will allow you to win only with bar symbols. The second coin will allow you to win with 7 symbols. The third coin will allow you to hit the top prize. Another example would be the Wheel of fortune machines. The first coin will allow you to win with all the symbols, but only the second coin will active the bonus spin and the top progressive prize.

Hope this gave you a better idea JohnnySlot,

TOPDOLLAR PLAYER