Fine Art is an art for Art's sake, whereas Illustration has a purpose. Art could be anything meaningless, which makes sense to some, while Illustration is a legit art that can be commercialized. Art is one of a kind and might not be copied, whereas Illustrations come in templates that can be used for promotional purposes, selling, mass marketing, etc. Fine Art is invaluable, whereas Illustration has a price; the better, the costlier. Illustration is mainly used for business purposes, which is why businesses have started collaborating with Illustrators, as it is perceived well by consumers.