First, it is P.P.S. It means post script, so p s s is post script script. p p s is post post script.
Anyway, a flash game is a game that is made using flash, a programming tool. The difference between a flash game and a regular is that flash is usable by many people, and an average person could make a game for it if they tried. A "normal" game is made using programming, and is harder to make.
A "normal" game is made using programming, and is harder to make.
Who said Flash wasn't made with Programming? :]
All in all, a Flash was made using a program called Adobe Flash, or any other program that produces a .swf file. Flashes are typically seen on the internet most, but they can be converted to a playable .exe format as well.