Don't forget it wss indicated that Silas had been killing for years before he came to Hollyoaks, remember he had that box of trophies. He's almost certainly notched up a few whilst on the run so I'd say his body count is probably dozens, if not higher.
Re mentality, they're very different. Silas sees ut as a holy mission so will just keep on snd on. Cameron always does it purely for self preservation so sees it as justified and doesn't enjoy it (unlike Silas and arguably Lindsey who found it a release) but dies it in such a wsy that people other than hus target can die as well and shows no sorrow or remorse for that. So is equally dangerous but in a different way.
Wasn't Toby Hollyoaks first serial killer?