Who: verwijst naar personenThis is the girl who helped me. That is the man who gave me some money.
Which: verwijst naar dieren en dingen
This is a picture of the house which he built himself. I like music which has a good beat.
That: verwijst naar dieren, dingen en personen (alleen als er GEEN KOMMAS staan)
There is the man who/that helped me. I like music which/that has a good beat.
Whose: verwijst naar bezit van personen, dieren en dingen (wiens/van wie)
The boy whose bike I borrowed is over there. That is the house whose owner died.