add-on vs constituent

add-on and constituent both are nouns.

Word	Noun	Adjective	Verb	Adverb
add-on	Yes	No	No	No
constituent	Yes	Yes	No	No

As nouns, constituent is a hypernym of add-on; that is, constituent is a word with a broader meaning than add-on:

add-on: a component that is added to something to improve it
constituent: an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system

Other hypernyms of add-on include component, element.

As nouns, constituent is a hypernym of add-on; that is, constituent is a word with a broader meaning than add-on:

add-on: a supplementary component that improves capability
constituent: an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system

Other hypernyms of add-on include component, element.

add-on (noun)	constituent (noun)
a component that is added to something to improve it	an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system
a supplementary component that improves capability	an abstract part of something
a software module that extends or enhances the capabilities of an existing application	(grammar) a word or phrase or clause forming part of a larger grammatical construction
	a member of a constituency; a citizen who is represented in a government by officials for whom he or she votes
	something determined in relation to something that includes it

add-on (adjective)	constituent (adjective)
	constitutional in the structure of something (especially your physical makeup)