changeless vs invariant

changeless is not a noun while invariant is a noun.

Word	Noun	Adjective	Verb	Adverb
changeless	No	Yes	No	No
invariant	Yes	Yes	No	No

As adjectives, changeless and invariant are synonyms defined as:

Other synonyms of changeless include constant, unvarying.

changeless (noun)	invariant (noun)
	a feature (quantity or property or function) that remains unchanged when a particular transformation is applied to it

changeless (adjective)	invariant (adjective)
not subject or susceptible to change or variation in form or quality or nature	unvarying in nature
unvarying in nature	unaffected by a designated operation or transformation
remaining the same for indefinitely long times