idealism vs quixotism

idealism and quixotism both are nouns.

Word	Noun	Adjective	Verb	Adverb
idealism	Yes	No	No	No
quixotism	Yes	No	No	No

As nouns, quixotism is a hyponym of idealism; that is, quixotism is a word with a more specific, narrower meaning than idealism:

idealism: impracticality by virtue of thinking of things in their ideal form rather than as they really are
quixotism: quixotic (romantic and impractical) behavior

Other hyponyms of idealism include romanticism, knight errantry.

idealism (noun)	quixotism (noun)
impracticality by virtue of thinking of things in their ideal form rather than as they really are	quixotic (romantic and impractical) behavior
elevated ideals or conduct; the quality of believing that ideals should be pursued
(philosophy) the philosophical theory that ideas are the only reality