It really depends on what section of organized crime it is. Usually anyone struck down by the mafia is over monetary disputes or betrayal. Mafiosos don't go into hospitals and just start shooting or bomb malls or anything like that.

Terrorists are extremists that commit murder out of hatred. In the mafia some people have to keep a lid on hatred as far as others go or it gets way out of hand. I wouldn't say its the same thing. I can see how some people would think so being as to how both a mafioso and a terrorist commit murder and break the law, but a mafioso would never hijack a plane and crash it into a building killing thousands of people.