sulfur vs benzoyl peroxide

Hi, i have back acne and this kinda verrrrryyy small white thingy, which im not sure wht tht is, but i think it kinda will grow into acne. So my back has reddish acne, those kinda white thing which on pic sometimes looks like verrrryyy tiny white bumps and some dark spots. It was only on my upper back tho, and its more on the middle part than on the back of my shoulders. Btw, im not sure if my acne is active or not, i cant really see white heads or anything just tiny tiny little bumps that turn to dark sport after wards. So which is better for: 1. The little red acne 2. Dark spots