idea vs suggestion

idea and suggestion both are nouns.

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

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

idea (noun)	suggestion (noun)
the content of cognition; the main thing you are thinking about	the act of inducing hypnosis
your intention; what you intend to do	an idea that is suggested
an approximate calculation of quantity or degree or worth	the sequential mental process in which one thought leads to another by association
a personal view	a proposal offered for acceptance or rejection
(music) melodic subject of a musical composition	persuasion formulated as a suggestion
	a just detectable amount