Solid green
Red.
orange
Red
Black
In billiards there are only 3 balls, 2 white 1 red.
In English Billiards there are 3 balls. White, white with spot (or yellow ball) and red.
The balls are all equal from a points perspective in English Billiards, Carom Billiards, and Pocket Billiards.
There are no points for pocketing a particular color ball in billiards. However, snooker awards 1 point for potting (the term used for pocketing by snooker players) a red ball.
15 ADD: Completely incorrect. This answer refers to pocket billiards, and more specifically "8 ball" or "boston" or "stripes and solids". In billiards, there are three balls. One of one color, and two of another.
Two Ball Billiards is a greek term which refers to ones Johnson and a pair of nuts.
The 2 Ball Billiards has but 3 balls, white, spot white & red. The blue is worth 5 in snooker.
There are none in English Billiards. In Carom Billiards, there are none. In the Pocket Billiards games, the 8 ball is the only black ball - 7 Ball has no 8 ball, hence no black ball, but all other games include the 8 ball, so, they have 1 black ball.