troy ounce vs troy unit

troy ounce and troy unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
troy ounce	Yes	No	No	No
troy unit	Yes	No	No	No

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

troy ounce: a unit of apothecary weight equal to 480 grains or one twelfth of a troy pound
troy unit: any of the unit of the troy system of weights

Other hypernyms of troy ounce include apothecaries' unit, apothecaries' weight.

troy ounce (noun)	troy unit (noun)
a unit of apothecary weight equal to 480 grains or one twelfth of a troy pound	any of the unit of the troy system of weights