Folk magic is often related to a locale such as Italian folk magic is the folk practices of Italy. Often it is steeped in lore and legend ie, Appalachian folk/granny magic.
Folk magic is considered low magic. It often incorporates the use of stones and plants and a lot of nature based ingredients, such as roots. Though practitioners can use any tool they wish you are less likely to find them using a chalice, or altar tile.
Folk magic differs from the practice of Wicca in many ways. You need not be religious to practice it, and it isn't ceremonial in nature. It isn't necessarily a must to be initiated. Many folk practitioners are solitary.
Essentially folk magic is none ceremonial magic or low magic. Whereas Wicca is high or ceremonial magic.
Examples of folk practices include:
Appalachian granny magic.
Hedge witchcraft, other forms of traditional witchcraft.
New England traditional witchcraft, based on practices of the lore and legend of New England, and utilizing plants, stones, and woods local to the area.