This is a question that I get a lot, so I thought it was blogworthy. This is my opinion, how I view the terms- it's also a very common opinion.
What’s the difference between Wicca and Paganism?
Paganism is an umbrella term used to describe several earth based and/or non-Abrahamic religions. Dianic, Goddess Path, Druidry, Wicca, Asatru, and more all fall within this term “Pagan.” Each of these paths (traditions) have their own holy days, their own way of doing ritual, their own traditional structure.
Wicca is a specific tradition. Those who are Wiccan celebrate the full moon (and sometimes the new moon), called Esbats, and at least eight seasonal celebrations called sabbats-usually in ceremony called rituals, sometimes followed by festivities and feasting. Wicca is often confused with witchcraft, as many Wiccans are also witches, but witchcraft is a practice, like prayer or meditation and many Wiccans do not practice the craft.
Wicca has no central dogmatic authority and each coven/group ( or solitary practitioner) is autonomous. There are many different traditions ( Like denomination) of Wicca. The practitioners of the original tradition of Wicca, called British Traditional Wicca, believe Wicca to be an initiatory religion (meaning one MUST be initiated) and can trace their initiatory linage back to the first high priest of Wicca
Due to the popularity of Wicca, many other traditions have sprouted up, and many solitary practitioners learn about different traditions and practice what calls to them. These solitary practitioners are more predominant than those in covens, and are referred to as Eclectic Wiccans.
The ethical core of Wicca is the Wiccan Rede - " An it harm none, do as ye will ". This advice is what most Wiccans try to live by as best as they can. There is no central book of Wicca (though a plethora of books have been written on the subject), and the practitioner usually keeps a journal of notes and experiences in a book usually referred to as a Book of Shadows (sometimes Book of Light or a Grimoire).
An eclectic Pagan will utilize concepts and ritual from different paths, finding the way that best works for them. An eclectic Wiccan will utilize concepts and will usually honor deities from different pantheon, but they still follow all of the concepts above, and also practice ritual using the traditional Wiccan ritual outline.
What’s the difference between Wicca and Witchcraft?
Wicca is a religious path, described above.
Witchcraft is a practice, like meditation or prayer that can be applied to any path. Most Wiccans are witches, but not all witches are Wiccan.
Witchcraft is the practice of magick, usually to create change on the physical plane of some sort (including changes in ourselves or other people). This is referred to as low magick or thaumaturgy. This differs from ceremonial magick- which is a different sort of path- and referred to as high magick or theurgy. Many people practice witchcraft and call it their religion- those people capitalize the name and call it Witchcraft, but most believe witchcraft to be a practice that can be applied to their personal spiritual path.