drop behind vs hang back

drop behind and hang back both are verbs.

Word	Noun	Adjective	Verb	Adverb
drop behind	No	No	Yes	No
hang back	No	No	Yes	No

As verbs, drop behind and hang back are synonyms defined as:

Other synonyms of drop behind include drag, drop back, get behind, trail.

drop behind (verb)	hang back (verb)
to lag or linger behind	to lag or linger behind