enormousness vs vastness

enormousness and vastness both are nouns.

Word	Noun	Adjective	Verb	Adverb
enormousness	Yes	No	No	No
vastness	Yes	No	No	No

As nouns, enormousness and vastness are synonyms defined as:

enormousness and vastness: unusual largeness in size or extent or number

Other synonyms of enormousness include grandness, greatness, immenseness, immensity, sizeableness, wideness.

enormousness (noun)	vastness (noun)
unusual largeness in size or extent or number	unusual largeness in size or extent or number