[Rudbaeck]

Yes, they are.

The bad sites use software algorithms to generate the seed, based on some rather deterministic pseudo-random seed. These, while better than they were a decade ago, are still kinda bad.

The good sites use a completely random physical device as seed, usually thermal noise. Or if they are cool and spendy radioactive decay. Both are actually, physically, random.

Now this has little practical effect, as even the bad method is about a billion billion times as random as the best Vegas dealer. It's just a question of how many billion billion times as random they are.

(Unless, ofcouse, someone fubars badly and manages a rerun of the Planet Poker fiasco of half a decade ago.)