pipe vs clay pipe

pipe and clay pipe both are nouns.

Word	Noun	Adjective	Verb	Adverb
pipe	Yes	No	Yes	No
clay pipe	Yes	No	No	No

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

pipe (noun)	clay pipe (noun)
a long tube made of metal or plastic that is used to carry water or oil or gas etc.	a pipe made of clay
a tube with a small bowl at one end; used for smoking tobacco
the flues and stops on a pipe organ
a tubular wind instrument
a hollow cylindrical shape