tubby vs roly-poly

tubby is not a noun while roly-poly is a noun.

Word	Noun	Adjective	Verb	Adverb
tubby	No	Yes	No	No
roly-poly	Yes	Yes	No	No

As adjectives, tubby and roly-poly are synonyms defined as:

Other synonyms of tubby include dumpy, podgy, pudgy.

tubby (noun)	roly-poly (noun)
	pudding made of suet pastry spread with jam or fruit and rolled up and baked or steamed
	a rotund individual

tubby (adjective)	roly-poly (adjective)
short and plump	short and plump