idea vs tune

idea and tune both are nouns.

Word	Noun	Adjective	Verb	Adverb
idea	Yes	No	No	No
tune	Yes	No	Yes	No

As nouns, tune is a hypernym of idea; that is, tune is a word with a broader meaning than idea:

Other hypernyms of idea include air, line, melodic line, melodic phrase, melody, strain.

idea (noun)	tune (noun)
the content of cognition; the main thing you are thinking about	the adjustment of a radio receiver or other circuit to a required frequency
your intention; what you intend to do	the property of producing accurately a note of a given pitch
an approximate calculation of quantity or degree or worth	a succession of notes forming a distinctive sequence
a personal view
(music) melodic subject of a musical composition

idea (verb)	tune (verb)
	adjust the pitches of (musical instruments)
	adjust for (better) functioning