De-pigmentation occurs every time a wound heals. This is due to the lack of melanin in the skin formed after a wound has healed. The texture of the new skin is very similar to the rest of the skin. The newer skin is pinker in colour due to the lack of melanin. The de-pigmentation will fade away after normal sun exposure.
Therefore the main difference between a scar and a skin de-pigmentation is that a scar will be visible after years and its texture is different to the normal skin. Skin de-pigmentation will fade away within 3 to 4 months.