difference in g4 & g3

[jjbpenguin]

I am an avid PC user but never really got into mac. I am thinking of getting a cheap g3 mac to play around with and was wondering what the difference in the g3 and g4 were. I have seen them both with identical processor speeds and ram and other stats, and was just wondering if I am missing something important about them or is is just changing the case?

 

[holyjunk]

Maybe the os? The newest version is os x I belive. I don't remember the other ones or really looked into it I guess. I would just get whatever is cheaper or whatever has the latest os.