The same substance, which is usually a combination of dead skin cells, oil, and sebum, consists of whiteheads and blackheads. Whiteheads, however, are pores that are closed while blackheads remain open. These major differences for blackheads vs whiteheads have an effect on how you should treat each type. Due to bacteria, dead skin, and sebum clogging and irritating your pores, both whiteheads and blackheads develop on your skin.