troy vs system of weights

troy and system of weights both are nouns.

Word	Noun	Adjective	Verb	Adverb
troy	Yes	No	No	No
system of weights	Yes	No	No	No

As nouns, system of weights is a hypernym of troy; that is, system of weights is a word with a broader meaning than troy:

troy: a system of weights used for precious metals and gemstones; based on a 12-ounce pound and an ounce of 480 grains
system of weights: a system of units used to express the weight of something

Other hypernyms of troy include weight.

troy (noun)	system of weights (noun)
a system of weights used for precious metals and gemstones; based on a 12-ounce pound and an ounce of 480 grains	a system of units used to express the weight of something