He's not comparable.. based on what?
I haven't seen an enormous amount of difference. Both are best on the drive. One takes less shots than the other is probably the one difference I've seen in the little I've watched. Other than the obvious physical attributes which don't really say much about skill & IQ, of which Westbrook also has quite a bit.
I don't over or underrate him. I haven't seen much. But he's clearly uncomfortable as a mid-range player.
Well let's see, one is a PG/SG and the other is a forward. As a PG/SG in today's game you better be either a. an excellent passer, b. an excellent shooter either off the dribble or a spot on shooter, c.combination of both. The role of a forward is much different. Should be a good rebounder while still having the ability to shoot from inside and mid. Ya giannis has no mid range game but he more than makes up for it with his attacking of the rim and absolute freak athletic ability to grab rebounds and dunk (his nickname was not given out of the blue). When he attacks the rhythm and is FULLY HEALTHY, there is no one regardless of size that can consistently stop him. He is the only player in that bucks team that can create shots for himself.
Westbrook IQ? dude lost his marbles after that 2016 humiliation vs Warriors and hasn't been the same since. In houston, if he goes in attack mode, it usually results in brick after brick after brick. If he stays passive, he is basically just a really good defender with not too much to contribute on offense. Makes that mid range bank shot from time to time, but his mid range game is nowhere near as consistent as before.
You could argue Giannis has single handedly contributed to this Bucks franchise being a #1 seed in 18-19 and 19-20. When has Westbrook single handedly led his team to 60+ wins in OKC? I'm waiting for the arguments "But the eastern conference is way easier than the western!!". Giannis #2 guy on his team was Middleton, a guy who barely made the all star team last season. Westbrook if anything was a sidekick to Durant and arguably Paul George, both head and shoulders above Middleton.
P.S. Completely forgot that Bucks were in the eastern conference finals last season, destroying a very capable Boston Celtics 4-1 before being stopped by the Robot Kawhi. Is he still a terrible playoff player?