mettle vs spunk

mettle and spunk both are nouns.

Word	Noun	Adjective	Verb	Adverb
mettle	Yes	No	No	No
spunk	Yes	No	No	No

As nouns, mettle and spunk are synonyms defined as:

Other synonyms of mettle include heart, nerve.

mettle (noun)	spunk (noun)
the courage to carry on	the courage to carry on
	material for starting a fire