fatty tissue vs flab

fatty tissue and flab both are nouns.

Word	Noun	Adjective	Verb	Adverb
fatty tissue	Yes	No	No	No
flab	Yes	No	No	No

As nouns, flab is a hyponym of fatty tissue; that is, flab is a word with a more specific, narrower meaning than fatty tissue:

fatty tissue: a kind of body tissue containing stored fat that serves as a source of energy; it also cushions and insulates vital organs
flab: loose or flaccid body fat

Other hyponyms of fatty tissue include atheroma, cellulite, puppy fat, mons, mons pubis, mons veneris, belly, paunch, love handle, spare tire.

fatty tissue (noun)	flab (noun)
a kind of body tissue containing stored fat that serves as a source of energy; it also cushions and insulates vital organs	loose or flaccid body fat