proxy vs placeholder

proxy and placeholder both are nouns.

Word	Noun	Adjective	Verb	Adverb
proxy	Yes	No	No	No
placeholder	Yes	No	No	No

As nouns, proxy and placeholder are synonyms defined as:

Other synonyms of proxy include procurator.

proxy (noun)	placeholder (noun)
a power of attorney document given by shareholders of a corporation authorizing a specific vote on their behalf at a corporate meeting	a symbol in a logical or mathematical expression that can be replaced by the name of any member of specified set
a person authorized to act for another	a person authorized to act for another