Blackheads and whiteheads both represent "clogged pores" meaning there is a collection of material within the duct of the sebaceous (oil) gland. They both represent type of comedones, which is a variety of acne
vulgaris. The difference between blackheads and whiteheads is only that blackheads are open to the air, which allows the contents of the pore to become oxidized and darken. Whiteheads contain the same material as blackheads, however because they are closed their contents cannot become oxidized and they remain white or skin colored. For this reason blackheads are called "open comedones" and whiteheads are "closed comedones".
The best way to keep your skin clear is to wash it regularly with a non-foaming face wash. Foaming face washes can be overly-drying, which causes your skin to produce more oil and makes you more likely to develop clogged pores. After you wash your face, dry it and apply a moisturizer. You should only use oil-free products which are labeled as "non-comedogenic" which means they will not cause comedones. You may also use products with alpha hydroxy acids to help your skin shed dead skin cells so that they will not build up and collect in pores, as this can also worsen acne. Please call your primary care physician
if you have any specific questions about skin care, or if you have any lesions that concern you to make sure they do not represent a more serious problem.