Four species of Ebolavirus cause disease in humans: Bundibugyo virus (BDBV), Sudan virus (SUDV), Taï Forest virus (TAFV) and Ebola virus (EBOV). EBOV is the most virulent species, killing 2111 people out of 3236 cases, which means two-thirds of infections lead to death. It was previously known as Zaire virus after the country where the disease was identified (now DR Congo) and is the species after which the others are named, what biologists call a type species. Here is an interesting chart showing the outbreaks in sequence by "Type" and number sequence.
EBOLA VIRUS DISEASE: OUTBREAK DEATHS BY SPECIES. Stream size is number of deaths per outbreak. Species: BDBV, Bundibugyo virus; EBOV, Ebola virus; SUDV, Sudan virus; TAFV, Taï Forest virus. (Data: WHO / CC BY: JV Chamary / Source: http://onforb.es/Y3YjoG)