Tatum is already a better shooter than Pierce ever was, but Pierce was a very strong guy. He very rarely got stripped going to rim, and could finish equally well with either hand. He also was awesome at finishing through contact. Pierce was wrong about Tatum finishing with either hand. He really doesn't do that yet very consistently. He does drive extremely well, though, and will probably end up being an even better scorer than Pierce some day.
I think Kawhi is a more like a 6'7 Marcus Smart, but with a really solid jump shot. Really long arms for his height. Tremendous defensive instincts. He gets his hands on everything and he's super strong.
Jaylen hasn't learned to use his hands defensively like that, at least yet. But he's quite a bit faster and quicker than Kawhi, and can jump better. He's also quite a bit ahead of where Kawhi was as a scorer at this point in his career. I'd be surprised if he doesn't turn out to be the better player.