^ It's Spock's body regenerated and it's Spock's memories he has inside him. Like they say, "A difference that makes no difference is no difference."
Save for Pike*, I think all the differences between TOS and ST XI are explainable, even the Romulans. I meant to mention this earlier, but there were so many other things I was typing in my first post that I just forgot. If Rabou (sp?) had never seen a Romulan before, he might be thinking they look like Vulcans, but he's not going to exclaim "You look just like the Vulcans!" in that situation. His first thought would be to attempt reasoning with Nero and then he can bring up the Romulans' resemblance to Vulcans later... except he gets killed. Afterward, there are 25 years between destruction of the Enterprise and the launching of the Kelvin where they can look at images transmitted and recorded from the event, so everyone knows what the Romulans look like.
* If this is an alternate reality all the way around that Old Spock and Nero traveled into, then Pike can be born earlier in addition to the Eugenics Wars happening later if it all.
R&D halting and being rethought, in light of Nero, can be the direct cause for the Enterprise's alternate appearance.
At the same time, I know that ST XI was a fig-leaf "have our cake and eat it too" reboot, so I'm willing to entertain Old Spock isn't even Spock from TOS, though I personally believe he is. I mean, you can rationalize the inconsistencies or you can call it like you see it. We could match each other into a stalemate.
Without being able to disprove an opposite opinion definitively it's like religion, literally, with its canon. You can interpret and analyze all you want, but there's nothing to prove concretely. My answer to anyone whenever they talk to me about religion is "I won't know until I'm dead and I'm not in a hurry to die."
Old Spock is Old Spock, however it means.