first-come-first-serve vs unreserved

first-come-first-serve and unreserved both are adjectives.

Word	Noun	Adjective	Verb	Adverb
first-come-first-serve	No	Yes	No	No
unreserved	No	Yes	No	No

first-come-first-serve (adjective)	unreserved (adjective)
not accepting reservations	not cautious or reticent
	not reserved