Hi,
Acne vulgaris (commonly called
acne) is a
skin disease caused by changes in the pilosebaceous units (
skin structures consisting of a hair follicle and its associated sebaceous gland).
A blackhead (medically known as an open comedo, is a yellowish or blackish bump or plug on the skin. A blackhead is a type of acne vulgaris. It is caused by excess oils that have accumulated in the sebaceous gland's duct.