All witches are pagans, but not all pagans are witches. Witchcraft is just one path of paganism. Other pagan paths include Druidry and Discordianism. Any earth-based religion or way of life can be labelled paganism.
Witchcraft is classed as paganism, and can also include many varied paths, too many to mention here.
It's a complex topic and well-worth exploring if you are interested.