I'm beginning to think this is completely different Universe,even before the Narada showed up. There are too many inconsistencies in technology for this just to be a different branch of the timeline from when the Narada shows up.
If that were the case, it would make...
No sense whatsoever that Spock Prime would warn his younger self about Khan, because if the timelines were truly separate, then Khan may never have existed or could be as different from Khan Prime as Mirror Brunt was from his usual self.
Plus the entire in-story justification for finding the Botany Bay and thawing Khan earlier - unless it was a timeline spinning off from Narada's incursion in 2233, there would be no need nor such effort expended by the writers in explaining how and why it happened differently to "Space Seed".
Nor would there be models of the NX-01 Enterprise and NX-Alpha on Admiral Marcus' desk if the technology was truly any different.
At the end of ST:TMP, Scotty said it would take the refitted Enterprise 3 days to reach Vulcan.
A shakedown cruise to Vulcan is a lot different to a maximum warp rescue mission.