Fat injections and fillers are both used to add volume to the face and smooth out wrinkles, but they differ in their composition and longevity. Fat injections use a patient's own fat, harvested from another area of the body, and can provide longer-lasting results than fillers. However, fillers are a non-surgical and more easily reversible option for those looking for a quick fix. The best option for an individual will depend on their specific goals and concerns.