Recognizing the different forms of acne is your first step in understanding the cause and treatment of your particular type. Acne is categorized into two groups; Non-inflammatory acne known as comedones, includes, blackheads and whiteheads. Inflammatory acne includes papules, pustules, nodules and cysts results from body’s fight to contain an infection. The noticeable difference is that the non-inflammatory acne is not red and painful because the body has not yet reacted to an infection with infection-fighting blood cells. While the inflammatory acne is painful, red, deep and swollen. It can last for weeks to months and leave dark marks, so it is important to treat it early.