unalterable vs changeless

unalterable and changeless both are adjectives.

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

As adjectives, unalterable and changeless are synonyms defined as:

unalterable and changeless: remaining the same for indefinitely long times

unalterable (adjective)	changeless (adjective)
not capable of being changed or altered	not subject or susceptible to change or variation in form or quality or nature
of a sentence; that cannot be changed	unvarying in nature
remaining the same for indefinitely long times	remaining the same for indefinitely long times