It usually depends on which culture you look at, but, in most cases, sorcery was looked apon as "white magic" which can be used as protection against witchcraft AKA "black magic."
Sorcery is the practice of what was once called Alchemy.
Witchcraft, (aka the Craft, Wicca and in some cases Paganism) is the following of an earth base belief system which includes but is not necessarily exclusive to the use of magic (high and low), Ritual celebration of the cycles of the year and phases of the moon, as well as herbalism and scrying. Contrary to what you see in movies and read in fiction, we are basicly good people, who live, work and play the same as others.