saw vs circular saw

saw and circular saw both are nouns.

Word	Noun	Adjective	Verb	Adverb
saw	Yes	No	Yes	No
circular saw	Yes	No	No	No

As nouns, circular saw is a hyponym of saw; that is, circular saw is a word with a more specific, narrower meaning than saw:

saw: a power tool for cutting wood
circular saw: a power saw that has a steel disk with cutting teeth on the periphery; rotates on a spindle

saw (noun)	circular saw (noun)
hand tool having a toothed blade for cutting	a power saw that has a steel disk with cutting teeth on the periphery; rotates on a spindle
a power tool for cutting wood
a condensed but memorable saying embodying some important fact of experience that is taken as true by many people

saw (verb)	circular saw (verb)
cut with a saw