collar vs neck opening

collar and neck opening both are nouns.

Word	Noun	Adjective	Verb	Adverb
collar	Yes	No	Yes	No
neck opening	Yes	No	No	No

collar (noun)	neck opening (noun)
the act of apprehending (especially apprehending a criminal)	an opening in a garment for the neck of the wearer; a part of the garment near the wearer's neck
a figurative restraint
a band that fits around the neck and is usually folded over
necklace that fits tightly around a woman's neck
a band of leather or rope that is placed around an animal's neck as a harness or to identify it
the stitching that forms the rim of a shoe or boot
a short ring fastened over a rod or shaft to limit, guide, or secure a machine part
anything worn or placed about the neck
(zoology) an encircling band or marking around the neck of any animal