Just looking at points they pretty much have the same career trajectory so far:
D+1
Buch 2 points in 10 KHL games, lots of minors games
Berg 3 points in 16 SHL games
D+2
Buch 29 points in 55 KHL games
Berg 12 points in 24 SHL games
D+3
Buch (so far) 29 points in 32 KHL games
Berg 45 points in 49 SHL games
Despite his size it seems like Buch goes into dirty areas more than Berggren likes to so hence my evaluation. I don't think he's super likely to be better than Burgers just that there's a chance.