And it was perfectly explained how, within the realms of sci-fi plausability, Spock was bought back to life.
Um, no. It really, really wasn't. His body died from severe radiation exposure from the intermix chamber itself, pure gamma radiation that was already melting his face off, and scarred his hands through protective gloves.
His body was physically throw into the sun (well meant to be). His "soul", an entirely mythical item from antiquity was somehow given to McCoy. *shrugs* on that bullshit from the start, science gave up, cried fuck you and went to get a drink for the rest of the movie series at that point.
Now, it had to just be a copy, since if he really just ripped out his "soul" and gave it to McCoy, his body would have dropped dead after the mind meld.
Months later, McCoy somehow is experiencing a merger of the two and is going to die if they don't surgically removie the spirit energy Spock mindviolated him with. Yeah....
They go to the Genesis planet, where we see that the Enterprise missed a STAR by a country mile, hitting a planet instead, even though the torpedo was fired with a velocity designed to delivery it across about 1 AU in a short time, meaning it's momentum should have really destroyed it on re-entry anyway. Somehow magically survives, "because" and 'soft lands' from that powerful shot, leaving no trace of having landed, intact, no crater etc
Spock's body then for some reason, is reduced to a single cell with the rest of it disappearing? no biological goop in the torpedo casing, which has no padding, so his body would have been smashed like crazy around inside it.
The planet magically brings this single cell to life from a totally dead, severely damaged body, and regrows it exactly how Spock was in life, without any of the external conditions that would have given rise to a lot of his features, and they just manage to get this empty vessel, with a brain that grew entirely infentile and atophed, to the ship where it's now in a coma for no reason.
Skip ahead to Vulcan, where a ceremony from legend is somehow able to be prepared inside half an hour, and performed perfectly even though no one of the was even alive when it was last performed. Even though many Vulcans could easily have been able to transfer their spirit mind to a sacrifite until a clone body was made at a younger age than before and put into that....
A religious ceremony that can somehow cause the local weather to change for dramatic effect, a storm caused by chanting no less, where a much much longer download, sorry, transfer of this magic soul thingy, into a brain that is totally synaptically different from the one it was contained in before, is overwritten, killing the new lifeform that lived only a few days, bringing a copy of Spock to life in that body.
In Into Darkness, Kirk is exposed to residual radiation from a matter/antimatter arc reaction and a percussive fall from the reaction vessel. There is no sign of damage to his skin and he lives longer than Spock did, able to move more.
He is only clinically dead a few moments before being put into a cryogenic chamber designed entirely to suspend a body as it is permanently.
Khan's blood stimulates the regenerative abilitu of the body itself, and being transfused with it, begins to repair all the cells damaged by the radiation.
McCoy informs him that the procedure was arduous, time consuming, and took a major toll on James' body. It left him in a coma for two weeks as Starfleet Medical continuined to repair the damage.
Essentially, they could have ressusitated him at the time, but with the radiation damage they would have been doing so only to have him die again shortly after. Khan's blood was able to allow them to revive him (and IRL, people have been brought back hours after "dying" even recently) all they had to do was keep him on life support while it did all the work.
And that work, was painful, slow, and I'd say even if it accelerated his cell division to replace the damaged or dead ones, still took time.
Comparing the two is just an insanely poor argument, one was bullshit mysticism brought in to backtrack on a decision they regretted a movie later, the other was using a villains trait to help save the hero, over like three weeks of pain and grouling hard work.