drop off vs drift off

drop off and drift off both are verbs.

Word	Noun	Adjective	Verb	Adverb
drop off	No	No	Yes	No
drift off	No	No	Yes	No

As verbs, drop off and drift off are synonyms defined as:

Other synonyms of drop off include dope off, doze off, drowse off, fall asleep, flake out, nod off.

drop off (verb)	drift off (verb)
change from a waking to a sleeping state	change from a waking to a sleeping state
fall to a lower standard
fall or diminish
retreat
remove (cargo, people, etc.) from and leave