Not confusing at all, good question.

Mark stated it well, similar impacts and similar resultant structural damage can have very different outcomes. "Less severe" impact does not always equal less severe symptoms.

In my case for example, my TBI was categorized as moderate to severe, and included a skull fracture with an epidural hematoma that required craniotomy surgery. It took about six months but my symptoms did resolve. Yet many people have relatively "minor" injury (at least as defined by measurable criteria such as GCS) and have affects that last years.

The majority of concussion patients fully recover, although multiple concussion increase the likelihood of persistent symptoms.

Wishing you well in your continued recovery.