@connectlandThe depth of the atrophy / pit or scar. A picture is the most helpful to determine. I need to see the shadows the scar makes from directional light or a flashlight. Many say they have severe scars when in reality they only have textural pits(This is not fat loss).

Rolling acne scar has nothing to do with fat loss or depth.

See the FAQ there are pictures there, pinned to the top of the scar treatments sub

Sometimes they can overlap, because cystic acne tends to reoccur in the same spots. Overtime, that repeated damage just literally eats away at the fat layer and leaves the classic sunken / aging face that is common in severe acne scars sufferers.

Usually fat loss is more widespread and happens over a large surface area, and can be severe enough to alter your facial appearance. Fat loss is "easier" to treat in that you canmass fill with fillers and immediately revolumize the face. This restores the contours of the face, lifting sunken areas. Often why scars look so much worse is because they lie in shadow. Once you lift up the cheeks, the area is no longer in shadow which improves the overall look of the face.