drop back vs drop behind

drop back and drop behind both are verbs.

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

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

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

drop back (verb)	drop behind (verb)
take position in the rear, as in a military formation or in the line of scrimmage in football	to lag or linger behind
to lag or linger behind