marginal vs peripheral

marginal is not a noun while peripheral is a noun.

Word	Noun	Adjective	Verb	Adverb
marginal	No	Yes	No	No
peripheral	Yes	Yes	No	No

marginal (noun)	peripheral (noun)
	electronic equipment external to the circuit board that contains the CPU of a computer

marginal (adjective)	peripheral (adjective)
of questionable or minimal quality	on or near an edge or constituting an outer boundary; the outer area
just barely adequate or within a lower limit	related to the key issue but not of central importance
at or constituting a border or edge
producing at a rate that barely covers production costs