sentry go vs sentry duty

sentry go and sentry duty both are nouns.

Word	Noun	Adjective	Verb	Adverb
sentry go	Yes	No	No	No
sentry duty	Yes	No	No	No

As nouns, sentry go and sentry duty are synonyms defined as:

Other synonyms of sentry go include guard, guard duty.

sentry go (noun)	sentry duty (noun)
the duty of serving as a sentry	the duty of serving as a sentry