overwhelm vs burden

overwhelm is not a noun while burden is a noun.

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

As verbs, burden is a hypernym of overwhelm; that is, burden is a word with a broader meaning than overwhelm:

Other hypernyms of overwhelm include charge, saddle.

overwhelm (noun)	burden (noun)
	weight to be borne or conveyed
	the central idea that is expanded in a document or discourse
	an onerous or difficult concern
	the central meaning or theme of a speech or literary work

overwhelm (verb)	burden (verb)
charge someone with too many tasks	impose a task upon, assign a responsibility to
overcome by superior force	weight down with a load
cover completely or make imperceptible
overcome, as with emotions or perceptual stimuli