double helix vs helix

double helix and helix both are nouns.

Word	Noun	Adjective	Verb	Adverb
double helix	Yes	No	No	No
helix	Yes	No	No	No

As nouns, helix is a hypernym of double helix; that is, helix is a word with a broader meaning than double helix:

double helix: a pair of parallel helices intertwined about a common axis
helix: a curve that lies on the surface of a cylinder or cone and cuts the element at a constant angle

Other hypernyms of double helix include spiral.

double helix (noun)	helix (noun)
a pair of parallel helices intertwined about a common axis	a structure consisting of something wound in a continuous series of loops
	a curve that lies on the surface of a cylinder or cone and cuts the element at a constant angle