reverse osmosis vs osmosis

reverse osmosis and osmosis both are nouns.

Word	Noun	Adjective	Verb	Adverb
reverse osmosis	Yes	No	No	No
osmosis	Yes	No	No	No

As nouns, osmosis is a hypernym of reverse osmosis; that is, osmosis is a word with a broader meaning than reverse osmosis:

reverse osmosis: (chemistry) a method of producing pure water; a solvent passes through a semipermeable membrane in a direction opposite to that for natural osmosis when it is subjected to a hydrostatic pressure greater than the osmotic pressure
osmosis: (biology, chemistry) diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal

reverse osmosis (noun)	osmosis (noun)
(chemistry) a method of producing pure water; a solvent passes through a semipermeable membrane in a direction opposite to that for natural osmosis when it is subjected to a hydrostatic pressure greater than the osmotic pressure	(biology, chemistry) diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal