What’s the difference between Vaser liposuction and a tummy tuck?

Vaser liposuction is a form of ultrasonic liposuction used to remove fat. The stated advantage of Vaser liposuction over standard liposuction is improved skin tone from the ultrasonic energy applied during fat removal. It is just as invasive as standard liposuction. It does not address the muscle separation or hanging skin. A tummy tuck or abdominoplasty typically utilizes some liposuction but focuses more on removing excess abdominal skin and tightening the abdominal wall to prevent bulges. 

Thank you for the question.   
Generally, the tummy tuck operation involves removal of excess skin/adipose tissue of the lower abdominal wall and re approximation of the abdominal wall muscles that may have spread with pregnancies and/or weight gain/loss. Liposuctioning is often used as a tool during the procedure.
Generally speaking, the “ideal” patient for tummy tuck surgery is one who has completed pregnancies, is psycho socially/emotionally/financially stable, has an excellent social support system surrounding him/her, is capable of arranging enough recovery time, does not smoke and who has reached a long-term stable weight.
All types of liposuction surgery, on the other hand, refers to operations that essentially suctions out adipose tissue. The operation does not involve any skin removal or re approximation of abdominal wall muscles. The best candidates for liposuction surgery of the abdominal wall are patients with good quality skin elasticity and a moderate degree of diet and exercise resistant adipose tissue superficial to the abdominal wall muscle layer. Patients who are significantly overweight, have significant abdominal wall laxity, and/or have lost a significant amount of skin elasticity are not generally good candidates.
My best suggestion: seek consultation with board-certified plastic surgeons who can demonstrate significant experience helping you achieve the type of outcome you will be pleased with. Best wishes.