idea vs burden

idea and burden both are nouns.

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

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

idea (noun)	burden (noun)
the content of cognition; the main thing you are thinking about	weight to be borne or conveyed
your intention; what you intend to do	the central idea that is expanded in a document or discourse
an approximate calculation of quantity or degree or worth	an onerous or difficult concern
a personal view	the central meaning or theme of a speech or literary work
(music) melodic subject of a musical composition

idea (verb)	burden (verb)
	impose a task upon, assign a responsibility to
	weight down with a load