hopeless vs impossible

hopeless is not a noun while impossible is a noun.

Word	Noun	Adjective	Verb	Adverb
hopeless	No	Yes	No	No
impossible	Yes	Yes	No	No

hopeless (noun)	impossible (noun)
	something that cannot be done

hopeless (adjective)	impossible (adjective)
without hope because there seems to be no possibility of comfort or success	not capable of occurring or being accomplished or dealt with
(informal to emphasize how bad it is) beyond hope of management or reform	(used of persons or their behavior) not acceptable or reasonable
certain to fail	totally unlikely
of a person unable to do something skillfully