bend vs hairpin bend

bend and hairpin bend both are nouns.

Word	Noun	Adjective	Verb	Adverb
bend	Yes	No	Yes	No
hairpin bend	Yes	No	No	No

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

Other hyponyms of bend include blind bend, blind curve, elbow.

bend (noun)	hairpin bend (noun)
curved segment (of a road or river or railroad track etc.)	a U-shaped bend in a road
diagonal line traversing a shield from the upper right corner to the lower left
movement that causes the formation of a curve
an angular or rounded shape made by folding
a circular segment of a curve

bend (verb)	hairpin bend (verb)
cause (an object) to assume a crooked or angular form
bend a joint
form a curve
change direction
turn from a straight course, fixed direction, or line of interest
bend one's back forward from the waist on down