hypothetical vs conjectural

hypothetical is a noun but conjectural is not a noun.

Word	Noun	Adjective	Verb	Adverb
hypothetical	Yes	Yes	No	No
conjectural	No	Yes	No	No

As adjectives, hypothetical and conjectural are synonyms defined as:

hypothetical and conjectural: based primarily on surmise rather than adequate evidence

Other synonyms of hypothetical include divinatory, hypothetic, supposed, suppositional, suppositious, supposititious.

hypothetical (noun)	conjectural (noun)
a hypothetical possibility, circumstance, statement, proposal, situation, etc.

hypothetical (adjective)	conjectural (adjective)
based primarily on surmise rather than adequate evidence	based primarily on surmise rather than adequate evidence