headpin vs bowling pin

headpin and bowling pin both are nouns.

Word	Noun	Adjective	Verb	Adverb
headpin	Yes	No	No	No
bowling pin	Yes	No	No	No

As nouns, bowling pin is a hypernym of headpin; that is, bowling pin is a word with a broader meaning than headpin:

headpin: the front bowling pin in the triangular arrangement of ten pins
bowling pin: a club-shaped wooden object used in bowling; set up in triangular groups of ten as the target

Other hypernyms of headpin include pin.

headpin (noun)	bowling pin (noun)
the front bowling pin in the triangular arrangement of ten pins	a club-shaped wooden object used in bowling; set up in triangular groups of ten as the target