invariable vs constant

invariable and constant both are nouns.

Word	Noun	Adjective	Verb	Adverb
invariable	Yes	Yes	No	No
constant	Yes	Yes	No	No

As nouns, invariable and constant are synonyms defined as:

Other synonyms of invariable include constant quantity.

invariable (noun)	constant (noun)
a quantity that does not vary	a quantity that does not vary
	a number representing a quantity assumed to have a fixed value in a specified mathematical context

invariable (adjective)	constant (adjective)
not liable to or capable of change	steadfast in purpose or devotion or affection
	uninterrupted in time and indefinitely long continuing
	unvarying in nature