largeness vs bigness

largeness and bigness both are nouns.

Word	Noun	Adjective	Verb	Adverb
largeness	Yes	No	No	No
bigness	Yes	No	No	No

As nouns, largeness and bigness are synonyms defined as:

largeness (noun)	bigness (noun)
the property of having a relatively great size	the property of having a relatively great size
large or extensive in breadth or importance or comprehensiveness
the quality of being pretentious (behaving or speaking in such a manner as to create a false appearance of great importance or worth)
the capacity to understand a broad range of topics