presupposition vs supposal

presupposition and supposal both are nouns.

Word	Noun	Adjective	Verb	Adverb
presupposition	Yes	No	No	No
supposal	Yes	No	No	No

As nouns, supposal is a hypernym of presupposition; that is, supposal is a word with a broader meaning than presupposition:

presupposition: the act of presupposing; a supposition made prior to having knowledge (as for the purpose of argument)
supposal: the cognitive process of supposing

Other hypernyms of presupposition include supposition.

presupposition (noun)	supposal (noun)
the act of presupposing; a supposition made prior to having knowledge (as for the purpose of argument)	a hypothesis that is taken for granted
	the cognitive process of supposing