yes, but nature magic and druidism is different. druidism would refer to what the night elves use, which is a divine magic as it follows a religion (similiar to the light, even though theres no specific deity its a faith).
on the other hand, harvest witches use arcane magic, and do not follow a druidic faith, to manipulate nature. this exact example can be seen in normal mages, who can make fireballs and iceballs but are not shamans for using the elements, rather they use the arcane to manipulate it.
harvest witches are quite literally mages who use nature, just like fire mages are mages who use fire and ice mages are ones that use ice.