marginal cost vs monetary value

marginal cost and monetary value both are nouns.

Word	Noun	Adjective	Verb	Adverb
marginal cost	Yes	No	No	No
monetary value	Yes	No	No	No

As nouns, monetary value is a hypernym of marginal cost; that is, monetary value is a word with a broader meaning than marginal cost:

marginal cost: the increase or decrease in costs as a result of one more or one less unit of output
monetary value: the property of having material worth (often indicated by the amount of money something would bring if sold)

Other hypernyms of marginal cost include cost, price.

marginal cost (noun)	monetary value (noun)
the increase or decrease in costs as a result of one more or one less unit of output	the property of having material worth (often indicated by the amount of money something would bring if sold)