leading vs directional

leading is a noun but directional is not a noun.

Word	Noun	Adjective	Verb	Adverb
leading	Yes	Yes	No	No
directional	No	Yes	No	No

leading (noun)	directional (noun)
thin strip of metal used to separate lines of type in printing
the activity of leading

leading (adjective)	directional (adjective)
going or proceeding or going in advance; showing the way	relating to or indicating directions in space
greatest in importance or degree or significance or achievement	relating to direction toward a (nonspatial) goal
having the leading position or higher score in a contest	showing the way by conducting or leading; imposing direction on
indicating the most important performer or role