dog collar vs necklace

dog collar and necklace both are nouns.

Word	Noun	Adjective	Verb	Adverb
dog collar	Yes	No	No	No
necklace	Yes	No	No	No

As nouns, necklace is a hypernym of dog collar; that is, necklace is a word with a broader meaning than dog collar:

dog collar: necklace that fits tightly around a woman's neck
necklace: jewelry consisting of a cord or chain (often bearing gems) worn about the neck as an ornament (especially by women)

dog collar (noun)	necklace (noun)
a collar for a dog	jewelry consisting of a cord or chain (often bearing gems) worn about the neck as an ornament (especially by women)
a stiff white collar with no opening in the front; a distinctive symbol of the clergy
necklace that fits tightly around a woman's neck