tour of duty vs enlistment

tour of duty and enlistment both are nouns.

Word	Noun	Adjective	Verb	Adverb
tour of duty	Yes	No	No	No
enlistment	Yes	No	No	No

As nouns, tour of duty and enlistment are synonyms defined as:

Other synonyms of tour of duty include duty tour, hitch, term of enlistment, tour.

tour of duty (noun)	enlistment (noun)
a period of time spent in military service	the act of enlisting (as in a military service)
	a period of time spent in military service