A nursery is a room in a house specifically designed for use by small children and babies. They play and sleep there.
Nursery can also be used in place of nursery school.
Does your son go to nursery school? = Does your son go to nursery? (Nursery school is more typical in British English, I think. In American English it is kindergarten, again I think.)
You could also use nursery to refer to the nursery in a hospital.
However, you can't use it to refer to a nursery plant - a nursery plant is not a place, unlike the others. You can use nursery to refer to a place where plants are grown and sold.
A creche is usually part of a large workplace and is where parents who work there can leave their children to be cared for during the work day.