You can only play 8ball with red/yellow balls .

9ball is obviously balls numbered 1-9 and you have to pot / hit them in order ie pot the 1 ball then the 2 etc etc etc .

I play 9ball quite a bit , takes more ball control imo as your limited to only one ball for your next shot and even then if you havent got a pot on you dont want to leave it open for the opponent .

What sucks about 9ball though is ......... you can pot 1 through 8 but if you miss the 9 and your oppo sinks it all that hard works gone bye bye

Also sucks when you get fucked by Golden Breaks and combo shots but it is a much better and quicker paced game than 8ball