K2 has a dense and hard sponge. K3 has a cake sponge. By rating K2 is 54 degrees and K3 is 53 degrees, but K3 feels much softer.
K2 topsheet is tackier by a lot K3 only has a whiff of tack. However K3 is more spinny, K2 is more direct. K2 is better for power play why K3 is much better for all-round technical play. I'm not saying K2 is bad at technical play or K3 is bad at powerplay.
K3 durability is crap.