service routine vs subroutine

service routine and subroutine both are nouns.

Word	Noun	Adjective	Verb	Adverb
service routine	Yes	No	No	No
subroutine	Yes	No	No	No

As nouns, subroutine is a hypernym of service routine; that is, subroutine is a word with a broader meaning than service routine:

Other hypernyms of service routine include function, procedure, routine, subprogram.

service routine (noun)	subroutine (noun)
a routine that can be used as needed	a set sequence of steps, part of larger computer program