We all have scars. Scars are imprints of incidents that will forever be ingrained into the skin of your story. They were once wounds that have been healed by the grace of time. In other words, they’re closed chapters. You can pick at them and they won’t bleed open.
Wounds on the other hand, are still proof of a pain that runs deep. Some wounds take forever to heal, and some don’t heal at all. Fears and insecurities are like wounds; it’s easier to bury them beneath all those layers because treating them would mean calling attention to them, and nobody has the time to deal with that.