unvarying vs changeless

unvarying and changeless both are adjectives.

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

As adjectives, unvarying and changeless are synonyms defined as:

Other synonyms of unvarying include constant, invariant.

unvarying (adjective)	changeless (adjective)
lacking variety	not subject or susceptible to change or variation in form or quality or nature
always the same; showing a single form or character in all occurrences	unvarying in nature
unvarying in nature	remaining the same for indefinitely long times