replacing vs novation

replacing and novation both are nouns.

Word	Noun	Adjective	Verb	Adverb
replacing	Yes	No	No	No
novation	Yes	No	No	No

As nouns, novation is a hyponym of replacing; that is, novation is a word with a more specific, narrower meaning than replacing:

replacing: the act of furnishing an equivalent person or thing in the place of another
novation: (law) the replacement of one obligation by another by mutual agreement of both parties; usually the replacement of one of the original parties to a contract with the consent of the remaining party

Other hyponyms of replacing include pitching change, supersedure, supersession, displacement, supplanting.

replacing (noun)	novation (noun)
the act of furnishing an equivalent person or thing in the place of another	(law) the replacement of one obligation by another by mutual agreement of both parties; usually the replacement of one of the original parties to a contract with the consent of the remaining party