That is a very common question that plastic surgeons answer all the time
Botox is a natural toxin that relaxes the muscles and thus makes dynamic wrinkles disappear. It does not fill the wrinkles. It works best on these type of wrinkles which are found on the forehead, the glabella( between the eyebrows) and the crows feet (side of the eye). Additionally it lifts the eyebrow when the technique is well done. On the lower half of the face Botox works as well but with less constant results. Its action lasts 6 months usually
Fillers are made from different materials but the most common is hyaluronic acid. They serve to fill the wrinkles and can be used at any type of wrinkle. This means that they work also on wrinkles were Botox has been insufficient alone. The most common wrinkles to be treated are the nasolabial ones(around the mouth). Fillers can also give volume to some regions like the cheeks or the lips. They usually last 12 months