obsessive vs obsessional

obsessive is a noun but obsessional is not a noun.

Word	Noun	Adjective	Verb	Adverb
obsessive	Yes	Yes	No	No
obsessional	No	Yes	No	No

As adjectives, obsessive and obsessional are synonyms defined as:

obsessive and obsessional: characterized by or constituting an obsession

obsessive (noun)	obsessional (noun)
a person who has obsessions

obsessive (adjective)	obsessional (adjective)
characterized by or constituting an obsession	characterized by or constituting an obsession