The terms zit and pimple are used interchangeably and have the same meaning, which means there is not a difference between the two terms. According to Teen Health, the word pimple is used to describe an acne blemish. These blemishes may include whiteheads, pustules and papules. The term zit can be considered a slang term for pimple.
According to the American Academy of Dermatology, there are several types of pimples and acne blemishes, including blackheads, whiteheads, papules, pustules, nodules and cysts. The latter are found very deep within the skin and often cause large lumps underneath the skin. Cysts and nodules lead to pitting and scarring more than other types of blemishes.
The most common forms of pimples are blackheads and whiteheads. Both are caused by blocked pores, according to the American Academy of Dermatology. In a whitehead, the pore closes up, resulting in a raised, white bump. In blackheads, the pore remains open, making the dark dirt and sebum visible. Papules and pustules form when the wall of the pore breaks. This allows the puss, bacteria and sebum to move into the skin. Cysts are deeper versions of papules and pustules. They are often very painful to the touch and frequently leave scars.