Answer:
Murder - is when you intend do kill someone on purpose. e.g if a burglar kills a woman and robs the house then that counts as murder considering he did it on purpose.
Manslaughter - if you went outside and someone attacked you but as defence you pushed him and accidently he dies then that would not count as muder considering you did it as a defence rather then doing it on purpose.
Added: SHORT ANSWER: Murder is killing somone with the INTENT to cause their death.
Manslaughter is death caused while committing an act in which the persons death was not intentional, or it was as the result of a careless act.