Concise answer
Acne marks are flat colour changes after inflammation, while acne scars alter the skin's surface as depressions or raised tissue. A person can have both, and they require different planning.
Red or brown marks may fade gradually, whereas ice-pick, boxcar and rolling scars reflect structural change.
Side lighting and in-person examination help separate pigment from depth before procedures are chosen.
When evaluation may help
Assessment is useful when active acne continues, the texture is difficult to classify or home treatment is causing irritation or darker marks.