unsubstantial vs insubstantial

unsubstantial and insubstantial both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unsubstantial	No	Yes	No	No
insubstantial	No	Yes	No	No

As adjectives, unsubstantial and insubstantial are synonyms defined as:

unsubstantial and insubstantial: lacking material form or substance; unreal

Other synonyms of unsubstantial include unreal.

unsubstantial (adjective)	insubstantial (adjective)
lacking material form or substance; unreal	lacking material form or substance; unreal
	lacking in nutritive value
	lacking solidity or strength