My impression: the ships are bigger and faster, weapons pack a bigger punch, but the world of Star Wars is generally low tech compared to Star Trek. Sure, Darth Vader might force toss Commander Riker around, storm troopers might blast up some red shirts, but the Enterprise-D vs. one star destroyer, the Ent-D will take a pounding, but they'll end up tech-ing their way out of it.
Oh, now that is an interesting thought and unexpected twist. Yes, Star Wars computer tech seems to lag behind Trek. Teching the tech might be an area Trek does better.
Except Han says the fleet couldn't destroy an entire planet while TOS seems quite confident in its ability to level a civilization.
Not exactly the same. Alderan was completely blown up. The entire Imperial star fleet might not have enough firepower to explode a planet into tiny pieces.
On the other hand, the Imperial star fleet can definitely lay waste to an entire planet, or turn it's civilization into slag, as we see in the case of Mandalore. This seems to be exactly what you are thinking about and what GO 24 would accomplish.
Plus, all that was established before the revelation of an entire star fleet of Star Destroyers with Death Star style planet killing cannons. Apparently Han was mistaken after all.