殺 殺 殺 殺 殺 殺 殺 -- 有 什麼 不 同 ?

Kill is simply an end to a live: I just killed a cat.
Slay is to kill something by violence.
Murder is killing a person with intention.
Massacre is an unnecessary, indiscriminate killing of a large number of human beings or animals, as in barbarous warfare or persecution or for revenge or plunder.
Assasinate is to kill a person (normally for political or religion reason)

Hope these are helpful!