Small changes in squat form shift which muscles work hardest. Elevated heels and a short step back hit your quads; sitting back and a longer step targets glutes. Wider stance or side lunges work your inner thighs. The same rules apply on the leg press.
When you have your heels elevated in a squat, you're going to work more of your quad. When you sit back to a box in a squat, you're going to work more of your glute. When you have your feet wider in a squat, you're going to work more of your inner thigh. When you keep your chest up and take a shorter step back, you're going to work more of your quad. When you lean your torso forward and take a bigger step back, you're going to work more of your glute. When you lunge to the side, you're going to work more of your inner thigh. When you have your feet lower down and closer together on the leg press, You're going to work more of your quad when you have your feet higher up. You're going to work more of your glute, and when you have your feet wider apart, you're going to work more of your inner thigh.
