casualness vs informality

casualness and informality both are nouns.

Word	Noun	Adjective	Verb	Adverb
casualness	Yes	No	No	No
informality	Yes	No	No	No

As nouns, informality is a hypernym of casualness; that is, informality is a word with a broader meaning than casualness:

casualness (noun)	informality (noun)
a casual manner	a manner that does not take forms and ceremonies seriously
The state of coming without regularity; of being occasional or incidental.	freedom from constraint or embarrassment