ersatz vs replacement

ersatz and replacement both are nouns.

Word	Noun	Adjective	Verb	Adverb
ersatz	Yes	Yes	No	No
replacement	Yes	No	No	No

As nouns, replacement is a hypernym of ersatz; that is, replacement is a word with a broader meaning than ersatz:

Other hypernyms of ersatz include substitute.

ersatz (noun)	replacement (noun)
an artificial or inferior substitute or imitation	the act of furnishing an equivalent person or thing in the place of another
	a person or thing that takes or can take the place of another
	an event in which one thing is substituted for another
	a person who follows next in order
	someone who takes the place of another person
	filling again by supplying what has been used up

ersatz (adjective)	replacement (adjective)
artificial and inferior