Difference between must_not and filter in elasticsearch

Question

Can someone explain to me what the difference between must_not and filter is in elasticsearch?

E.g. here (taken from elasticsearch definitive guide), why isn\'t must_not

Answer 1

Basically, filter = must but without scoring.

must_not expresses a condition that MUST NOT be met, while filter (and must) express conditions that MUST be met in order for a document to be selected.