peg down vs nail down

peg down and nail down both are verbs.

Word	Noun	Adjective	Verb	Adverb
peg down	No	No	Yes	No
nail down	No	No	Yes	No

As verbs, peg down and nail down are synonyms defined as:

Other synonyms of peg down include narrow, narrow down, pin down, specify.

peg down (verb)	nail down (verb)
define clearly	make final; put the last touches on; put into final form
fasten or secure with a wooden pin	define clearly
	succeed in obtaining a position