What is the difference between pool and billiards and snooker?

Billiards: Pocketless table (5 x 10 ft), generally played with 3 balls. Different games include 3-cushion, 5 pin, or straight rail, although there are other options. The balls are slightly bigger than pool or snooker balls. Pool: Six pockets on a table (4.5 x 9 ft). Popular games include 8 ball, 9 ball, 10 ball, one pocket, and straight pool. The balls are numbered 1-15 and the games take advantage of them in various ways. Snooker: Big table with six pockets (6 x 12 ft). Pocket openings have rounded corners so you have to be more exact with shots. Snooker balls are a little smaller. There are 15 red balls, and 6 colored balls plus the cue ball.  more