The words "witchcraft" and "sorcery" tend to be used interchangeably, but are they REALLY interchangeable? I would say "no" as I don't think they're the same thing, though there's a lot of overlap. In one of her books Sybil Leek (and I've heard it repeated elsewhere since) makes the statement that witches use a magical power or ability inherent in themselves, whiles sorcerers create magic my manipulating external objects. This is more or less my own feeling on the matter. While most people can learn to do magic, using various folk traditions, I don't think just anybody can be a witch. To be a witch, I think one has to be either born with an innate ability, or have it bestowed upon them, whether by spirits or deities or some other mechanism. Most folk magic practitioners ,in my opinion, would fall into the "sorcerer" category; indeed, many would be horrified if you were to call them a "witch" as their traditions claim that witches are evil.
Likewise, what's the difference between a "witch" and a "magician?" One could make the case that "magicians do high magic, and witches do low magic" but this isn't always true. Instead, as above, I would say that a witch does magic based on an internal power/skill, and a magician does magic utilizing external forces, whether by harnessing the elements or calling up spirits. Ceremonial Magic tends to be incredibly complicated and involved, focuses on lofty and non-material things, and almost always uses a strong Christian framework. While these elements can be found, to a lesser degree, in witchcraft, they do not make up the bulk of the practice as they do here.
Finally, and this is a bit of a controversial view, but I think Witchcraft has a religious angle, while sorcery or high magic may not. Obviously, we've got magical religions like Wicca and Feri, but even in "traditional" practices, one almost ALWAYS finds a deity at the center of it. Traditionally, this was usually a Horned God, though the Goddess Diana and others were also said to be the patrons of various covens. Likewise, in my view a Witch would always have at least some dealings with spirits and the Otherworld, which sets them apart from people who may do simple folk magic or even from Pagans who cast a spell every now and again.
So, merely doing magic doesn't make you a witch. An atheist, for example, who casts love spells wouldn't be a witch, nor would a Christian who calls on angels and casts simple charms. To be a witch is to be set apart, to have the power within, power that doesn't rely on tools or herbs or written spells. These things are tools, yes, and of a great aid, but they do not create the magic as they do in non-Witchcraft traditions. In my studies and networking, the people who really stood out, who I think of as true witches, did not have to "become" anything, or learn from others what they were. They always KNEW they were witches, and the training and practice later was only the icing on the cake. It's not to say that they (or myself, for that matter) are "better" than other people, just that they have a destiny and a call that is different from those who learn magic and use their skills purely for Earthly needs and desires.