circumcision scars can be numerous. the darker ring is commonly referred to as one, however, there is actually a difference between the lighter skin of the foreskin, and the skin of the penile shaft. the lighter skin secretes oils which act as a moisturizing lubricant to the glans penis,helping to maintain it's sensitivity, and when combined with the sloughing of dead skin cells, is the major component of 'smegma. If you notice the dick head on a cut man, the glans is not shiny, slick, or as smooth. This is because the cut dick, in essence, has a 'calloused' glans penis, & therefore, is much less sensitive.(Just one of the major drawbacks of circumcision),
Other circumcision scars can refer to differences in skin pigmentation and actual true scarring which can occur during a botched circumcision. (Which happens more often than what one may commonly think!)
Sometimes this can happen on the shaft, OR the dick head, and produce scar lines, differences in dick head shape, shaft contouring, etc..
Dispite my arguments against it, my son was circumcised, and ended up with a botched circumcision,where his shaft skin grafted to the head of his dick. --MOST unpleasant,
which would have left him with a deformed member, had I not insisted we go back a couple of years later and have it repaired.
It's worth doing your research if youre considering the proceedure, especially considering your age.