What are the two extremes of memory recall ability?

The answer is: total recall and not being able to recall anything at all

For most people, we can only recall the memories that we encountered often, relevant to our needs, and somehow have an emotional value to us. The rest of memories that do not belong in these categories still exist in our brain, but they are vague and it's hard for us to recall them.

The two extremes deviate from this normal occurrence. Some people have eidetic memory that make them able to remember every single information that they obtain in their life even to the smallest details. Some people are on the extreme opposite while they can't even remember basic information that they receive.