rich vs well-off

rich is a noun but well-off is not a noun.

Word	Noun	Adjective	Verb	Adverb
rich	Yes	Yes	No	No
well-off	No	Yes	No	No

rich (noun)	well-off (noun)
people who have possessions and wealth (considered as a group)

rich (adjective)	well-off (adjective)
possessing material wealth	fortunately situated
having an abundant supply of desirable qualities or substances (especially natural resources)	in fortunate circumstances financially; moderately rich
suggestive of or characterized by great expense
high in mineral content; having a high proportion of fuel to air
causing indignation due to hypocrisy
affording an abundant supply
strong; intense
marked by great fruitfulness
pleasantly full and mellow
marked by richness and fullness of flavor
containing plenty of fat, or eggs, or sugar
of great worth or quality
very productive