yes, kalmah sounds somewhat like children of bodom. some of the songs are played in the same scale and same tuning as children of bodom. but their styles are different. Children of bodom's older stuff is very much neo-classical and has a lot of sweep picking in it. Kalmah stuff doesnt have as much sweeps in it, i think. In contrast I hear a lot of tremolo picking in kalmah's songs which make them sound more evil and black metal kind of, and in COB, i only heard tremolo picking in Something Wild. I find Kalmah also more melodic than COB, their solos kind of like Michael Amott's stuff - extremely melodic.
COB and Kalmah are both good in their own ways. I am not going to put down any of these bands because they are both great! I love them both equally.