subroutine vs subprogram

subroutine and subprogram both are nouns.

Word	Noun	Adjective	Verb	Adverb
subroutine	Yes	No	No	No
subprogram	Yes	No	No	No

As nouns, subroutine and subprogram are synonyms defined as:

subroutine and subprogram: a set sequence of steps, part of larger computer program

Other synonyms of subroutine include function, procedure, routine.

subroutine (noun)	subprogram (noun)
a set sequence of steps, part of larger computer program	a set sequence of steps, part of larger computer program