nonce word vs hapax legomenon

nonce word and hapax legomenon both are nouns.

Word	Noun	Adjective	Verb	Adverb
nonce word	Yes	No	No	No
hapax legomenon	Yes	No	No	No

As nouns, nonce word and hapax legomenon are synonyms defined as:

nonce word and hapax legomenon: a word with a special meaning used for a special occasion

nonce word (noun)	hapax legomenon (noun)
a word with a special meaning used for a special occasion	a word with a special meaning used for a special occasion