software vs subprogram

software and subprogram both are nouns.

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

As nouns, subprogram is a hyponym of software; that is, subprogram is a word with a more specific, narrower meaning than software:

software: (computer science) written programs or procedures or rules and associated documentation pertaining to the operation of a computer system and that are stored in read/write memory
subprogram: a set sequence of steps, part of larger computer program

software (noun)	subprogram (noun)
(computer science) written programs or procedures or rules and associated documentation pertaining to the operation of a computer system and that are stored in read/write memory	a set sequence of steps, part of larger computer program