Aside from rushing out to close the angle in 1v1 situations, which any goalkeeper worth his salt will do now anyway, I'm struggling to see any real similarities between the two.
Karius wasn't anywhere near as comfortable with his feet despite being made out to be Ederson Mk II on here.
No idea if anyone ever made Karius out to be Ederson Mk ll, but I think he was pretty comfortable with the ball at his feet, and good at moving it on quickly which seemed to fit how we play very well. Good short passing game too. His long passing always seemed pretty poor though, and Alisson smashes him at this, and is a much better shot stopper too as well as being a much more calming, confident presence and just, well, better generally.
Still, we probably shouldn't get into it about Karius again. From memory you were in the "Karius is shite" camp, I was in the "Karius is alright" camp, and there never seems to be much bridging of that gap. It matters not anymore, anyway; Alisson is simply much better than any keeper we've had in years, and it's great.