fattiness vs blubber

fattiness and blubber both are nouns.

Word	Noun	Adjective	Verb	Adverb
fattiness	Yes	No	No	No
blubber	Yes	No	Yes	No

As nouns, blubber is a hypernym of fattiness; that is, blubber is a word with a broader meaning than fattiness:

Other hypernyms of fattiness include avoirdupois, fat, fatness.

fattiness (noun)	blubber (noun)
having the property of containing fat	excess bodily weight
	an insulating layer of fat under the skin of whales and other large marine mammals; used as a source of oil

fattiness (verb)	blubber (verb)
	cry or whine with snuffling
	utter while crying