groundwork vs supposition

groundwork and supposition both are nouns.

Word	Noun	Adjective	Verb	Adverb
groundwork	Yes	No	No	No
supposition	Yes	No	No	No

As nouns, supposition is a hypernym of groundwork; that is, supposition is a word with a broader meaning than groundwork:

groundwork: the fundamental assumptions from which something is begun or developed or calculated or explained
supposition: a hypothesis that is taken for granted

Other hypernyms of groundwork include assumption, supposal.

groundwork (noun)	supposition (noun)
preliminary preparation as a basis or foundation	a hypothesis that is taken for granted
lowest support of a structure	the cognitive process of supposing
the fundamental assumptions from which something is begun or developed or calculated or explained	a message expressing an opinion based on incomplete evidence