There are basically 4 types of highlights: basic foil highlights, baliage or "hair painting," chunking or "piecing" and lowlighting.
Foil highlights introduces lightness and brightness with more of a natural appereance/
Baliage, or "hair painting," allows your hair colorist to add highlights to the hair in large or smaller swaths.
Lowlighting allows your hair colorist to add depth and dimention This gives hair color more contrast.