notion vs first blush

notion and first blush both are nouns.

Word	Noun	Adjective	Verb	Adverb
notion	Yes	No	No	No
first blush	Yes	No	No	No

As nouns, first blush is a hyponym of notion; that is, first blush is a word with a more specific, narrower meaning than notion:

Other hyponyms of notion include presence, effect, hunch, intuition, suspicion.

notion (noun)	first blush (noun)
(usually plural) small personal articles or clothing or sewing items	at the first glimpse or impression
a general inclusive concept
an odd or fanciful or capricious idea
a vague idea in which some confidence is placed