Wicca is a specific tradition of witchcraft
I'm sorry, but no it isn't. They are two seperate entities running parallel to each other.
A witch is somebody who casts spells using the natural cycles as allegory and guide. He/she might also summon spirits, work ritual magick, and so forth. These spells can be of any nature at all.
A Wiccan, on the other hand, is a spiritual descendent of Gerald Gardner and/or Alex Sanders and operates under the tenet "An it harm none, do as thou wilt." Although there are many schools of Wicca now - from Faery to Seax to Celtic (the word eclectic crops up time and again in Wiccan self-description) - the general precepts is that the Wiccan worships the Goddess and Horned God (usually with the Goddess in the precedence). The Goddess and God are seen as manifest in all other gods and goddesses, the Divine is easily assessed and recognised in many fms. However, this aspect is shared with some other witches.
Essentially, all Wiccans are witches but not all witches are Wiccans. Within the category of Witchcraft, there are more differentiations. This includes Traditional Witchcraft, which is animistic and polytheistic like many other types of magickal belief, but which admits no superioer entity. The God and Goddess are seen as innate in nature rather than external lofty forces (most Wiccans will see them as both), although spirits will often be called upon to help the witch meet her aim. These spirits are perceived as equal but different, as is all in the cosmos., There is no hierarchy in Traditional Witchcraft, while in Wicca, deities exist are are obviously our "superiors". (Not in the Judeo-Christian/Islamic sense. The deities are respected as evident in natural things - the trees and earth, for example, and the stars and sky - and there is no aspect of fear or punishment in the sense of divinity.)
Wicca tends to be more ritualistic than Traditional Witchcraft, which is simple and often involves no paraphernalia atall. Traditional Witchcraft does not involve casting a Circle, for example, but all places are seen as sacred. The Traditional witch must therefore be naturally fully attuned to magickal thought processes at all times. A Wiccan, on the other hand, can afford to "be mundane" (sometimes a necessity in this world), knowing as she does that small ritual will restore her to her magickal persona and create a spere in which the worlds intermingle.
Wicca is ethical, while Traditional Witchcraft is amoral. In Traditional Witchcraft, emphasis is placed on taking responsibility for one's actions and on intent. The forces of the Universe are seen as neutral (like weather), rather than good or evil. Curses and hexes are used for self-preservation, whereas a Wiccan would never curse, believing in the law of threefold return and in the ethics of "An' it harm none."
Like Wiccans, Traditional witches celebrate the seasonal sabbats and lunar esbats. however, no invocations to theLords of the Watchtowers would precede a Traditional ritual; if protection were needed, spirits and elementals might be summoned to assist, but the mode would not be high magickal. Clothes would be kept on in most Traditional Witchcraft covens, rather than working in ritual robes, or skyclad, as most Wiccans tend to do.
There are witches that belong to neither of these categories, especially as magick and spell-casting have become popular since the 1960s. Information has exited the broom cupboard and landed inteh most public of forums. Thousands of books have become available, leading to this characteristic awareness of natural cycles, the widespread practice of maick, the emergence of new covens, and self-initiation. There are now as many types of witch as there are individuals practising the Craft.