idea vs substance

idea and substance both are nouns.

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

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

idea (noun)	substance (noun)
the content of cognition; the main thing you are thinking about	the real physical matter of which a person or thing consists
your intention; what you intend to do	a particular kind or species of matter with uniform properties
an approximate calculation of quantity or degree or worth	the property of holding together and retaining its shape
a personal view	the idea that is intended
(music) melodic subject of a musical composition	the choicest or most essential or most vital part of some idea or experience
	content communicating a message; what something is about
	considerable capital (wealth or income)
	material of a particular kind or constitution