Liposuction is just the removal of fat cells from certain areas of your body using a small incision and suction. A tummy tuck involves the removal of loose skin and then re-stitching it. Liposuction is reserved for areas that have relatively elastic skin that doesnt require any stitching.
During liposuction the doctor will use a machine to literally suck out excess fat from areas of the body. During a tummy tuck the suregon will cut off excess skin, design a new belly button and sew things back up.
Liposuction refers to removing fat from any part of the body, a tummy tuck involves removing excess fat from the body and removing parts of the skin to make the tummy look tight again. That means that a tummy tuck is liposuction, but liposuction is not necessarily a tummy tuck.
Liposuction is a procedure performed with a device called a cannula. It is like a large bore syringe. The doctor inserts it under the skin and sucks out subcutaneous fat and some fluids. A tummy tuck involves surgically removing skin, in some ways like a face lift.