fatty vs fat

fatty and fat both are nouns.

Word	Noun	Adjective	Verb	Adverb
fatty	Yes	Yes	No	No
fat	Yes	Yes	Yes	No

As adjectives, fatty and fat are synonyms defined as:

fatty (noun)	fat (noun)
a rotund individual	excess bodily weight
	a kind of body tissue containing stored fat that serves as a source of energy; it also cushions and insulates vital organs
	a soft greasy substance occurring in organic tissue and consisting of a mixture of lipids (mostly triglycerides)

fatty (adjective)	fat (adjective)
containing or composed of fat	having an (over)abundance of flesh
	containing or composed of fat
	marked by great fruitfulness
	lucrative
	having a relatively large diameter

fatty (verb)	fat (verb)
	make fat or plump