Just in case the former WU got you confused, here's a rough breakdown on what he's talking about--Potti is a standard fruit machine, with or without a doubler. Keno is a lotto/bingo machine where you choose up to ten numbers out of forty. (Payoffs start at three hits, and keep on going.)Poker is your general poker machine.
Pajatso is another ball of wax entirely, being a semi-skill game where the object is to nudge coins down slots, with a combination of strategic positions and twitch. It's very hard, and there are even Pajatso tournaments held by RAY across Finland. In terms of play, it's more like bagatelle, or the American Cascade of Silver, than standard casino fare.
In general, RAY machines use more sophisticated graphics and design than what I've seen Bally use: wins are signaled by a bouncy, friendly-sounding melody, court cards are all attractive contemporary figures, and the general image is that of a wholesome, fun, activity worlds apart from say, Las Vegas.
Wonder how I know all this? RAY maintains a website http://Pelaamo.Ray.fi, that has sample games to try and hone your technique. It's mostly in Finnish, but a clever Everythingian could probably figure out all you need to know in a half-hour...