intention vs idea

intention and idea both are nouns.

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

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

intention: an anticipated outcome that is intended or that guides your planned actions
idea: your intention; what you intend to do

Other hyponyms of intention include mind, cross-purpose, final cause, sake, view, will.

intention (noun)	idea (noun)
an act of intending; a volition that you intend to carry out	the content of cognition; the main thing you are thinking about
an anticipated outcome that is intended or that guides your planned actions	your intention; what you intend to do
(usually plural) the goal with respect to a marriage proposal	an approximate calculation of quantity or degree or worth
	a personal view
	(music) melodic subject of a musical composition