The main difference between the two exercises is the placement of your feet.
During a regular squat, the feet are placed hip-width apart, and the toes face forward or slightly out. When doing a sumo squat, the feet are in a wide stance with the toes turned out at an even greater angle.
Because of the foot positioning, the muscles emphasized in each of these variations differs, too.
Both work the glutes, quadriceps, hamstrings, hip flexors and calves.
However, the sumo squat places more emphasis on the inner thigh adductors, which move your legs in toward your body, and glutes. Depending on your core strength, you may also find sumo squats an additional challenge to your balance, as you’re putting your body into a new alignment and need stability to keep from rocking forward or back on your heels.