roller skate vs skate

roller skate and skate both are nouns.

Word	Noun	Adjective	Verb	Adverb
roller skate	Yes	No	Yes	No
skate	Yes	No	Yes	No

As nouns, skate is a hypernym of roller skate; that is, skate is a word with a broader meaning than roller skate:

roller skate: a shoe with pairs of rollers fixed to the sole
skate: sports equipment that is worn on the feet to enable the wearer to glide along and to be propelled by the alternate actions of the legs

As verbs, skate is a hypernym of roller skate; that is, skate is a word with a broader meaning than roller skate:

roller skate: travel on shoes with steel or rubber rollers attached to their soles
skate: move along on skates

roller skate (noun)	skate (noun)
a shoe with pairs of rollers fixed to the sole	large edible rays having a long snout and thick tail with pectoral fins continuous with the head; swim by undulating the edges of the pectoral fins
	sports equipment that is worn on the feet to enable the wearer to glide along and to be propelled by the alternate actions of the legs

roller skate (verb)	skate (verb)
travel on shoes with steel or rubber rollers attached to their soles	move along on skates