My guess is that the change in the timeline has permitted different technologies to be utilized in regards to the Enterprise. Keep in mind that this one is more than double the size of the origional, so it would make sense if they weasel out of it that way. Probably.
That would work if they had remotely hinted at in some way. Just a mention that they discovered some new technology in researching the Kelvin disaster or whatever, but as it is laid out there is a 25 year gap where the only real noted affect is in Kirk's personality and outlook on life.
Add in that the dialog still suggests impulse engines, thrusters, and warp drives, and it seems as if the writing went out of their way to suggest that the technology is the same.
But it is a minor detail mostly unrelated to the story, and I did overlook it.
The change in ship size and minor design differences is actually a throwback to the old series (and also compounds the liftoff technology even more). In the failed Christopher Pike pilot the Enterprise was small, only ~250 people on board. In the Kirk pilot it was bumped up to over ~400 people on board, and in the rest of the series it was slightly bigger having between 400-500 people on board and is even referred to as a flying city at one point, which then leads to the design and concept changes going into The Next Generation timeline where it literally is a flying city where the crew only makes up approximately half the passengers as it also acts as a diplomatic transport.
Honestly, if Star Trek weren't something that my father put into my mind earlier than I can remember none of this would even stand out to me.
One change I found very nice is the non-human species. There were many more species that appeared to be more than mutated humans. But they were done well. It had an old Star Wars feel to it, where you felt that you could see them actually existing and working based on known science. It avoided the Star Wars prequels that overdid the CGI and left me wondering how some of them could exist on gravity even remotely close to Earth's.
It definitely gave it an update that worked with known possible science as well as utilizing the technology available today. In the 60's I think it would have made the series less popular to have less-human looking species because of prejudices at the time. No one could like them. Now we are at a stage where people easily take a liking to non-human looking creatures. It is a sign of the effect that Spielberg and Lucas have had on sci-fi. Arthur C Clark deserves some credit, but non of his non-human species ever made it on to TV or film. I would love a Rama film series.
