Question is are all 3" balls the same...
No, but not by what you mean.
All 3" TB balls will work in all 3" TBs.
The differences are in weight, color, translucency, and shine. (Not counting wear changing the feel.)
The atari and happs are the same; happs TBs are the current make of the old atari TBs. IIRC, the happs balls are a very little heavier than the betson/wico. In general, solids are heavier than translucents.
Besides that, yes they are the same