turn back vs double back

turn back and double back both are verbs.

Word	Noun	Adjective	Verb	Adverb
turn back	No	No	Yes	No
double back	No	No	Yes	No

As verbs, turn back and double back are synonyms defined as:

Other synonyms of turn back include backtrack.

turn back (verb)	double back (verb)
go back to a previous state	retrace one's course
turn inside out or upside down
hold back, as of a danger or an enemy; check the expansion or influence of
retrace one's course
force to go away; used both with concrete and metaphoric meanings