Confusion about this Ebola stuff

I don't understand how a nurse in full protective gear can get the virus and paramedics who are only wearing face masks don't get it? I realize my questions have probably been asked a hundred times but seriously, how can these people be wearing hazmat suits and get Ebola and people over here are exposed, not wearing suits, thus far not getting the virus. Are we talking about a different strain, or what? What the hell is going on?