sequence vs sequential

sequence is a noun but sequential is not a noun.

Word	Noun	Adjective	Verb	Adverb
sequence	Yes	No	Yes	No
sequential	No	Yes	No	No

sequence (noun)	sequential (noun)
the action of following in order
film consisting of a succession of related shots that develop a given subject in a movie
a following of one thing after another in time
several repetitions of a melodic phrase in different keys
serial arrangement in which things follow in logical order or a recurrent pattern

sequence (adjective)	sequential (adjective)
	in regular succession without gaps

sequence (verb)	sequential (verb)
arrange in a sequence
determine the order of constituents in