Actually, I think its exactly the same as Spock. But I don't think post-Genesis Spock is the same being as the one who died saving the Enterprise. He made a copy of his katra/soul and uploaded it to McCoy's brain (he obviously didn't do a live transfer as he was still functional after the meld. The original katra died in the Enterprise's Engine Room. The copy was transferred to a cloned body. And even then the copy couldn't have been that good because Spock 2.0 was missing knowledge and had to have his mind "retrained" on Vulcan. Sure, all of his friends viewed him as the same person (as did I when I first saw TSFS), but I now have doubts.
I don't try and hard science Trek too much. For me, Trek is about the "soft science" of examining social issues as well as morality. I may be in the minority there, however.
For me, Spock is a psychic being who transferred his katra before his death. Part of his soul, which is a literal thing in Star Trek. His soul was returned to his body, which has been physically rejuvenated. So I think there's a definite difference between the two situations.
But yes, you could make an argument Data 2.0 is also kind of Tuvix-ey. He's less Data than a Composite Entity.