usance vs period of time

usance and period of time both are nouns.

Word	Noun	Adjective	Verb	Adverb
usance	Yes	No	No	No
period of time	Yes	No	No	No

As nouns, period of time is a hypernym of usance; that is, period of time is a word with a broader meaning than usance:

usance: the period of time permitted by commercial usage for the payment of a bill of exchange (especially a foreign bill of exchange)
period of time: an amount of time

Other hypernyms of usance include period, time period.

usance (noun)	period of time (noun)
accepted or habitual practice	an amount of time
(economics) the utilization of economic goods to satisfy needs or in manufacturing
the period of time permitted by commercial usage for the payment of a bill of exchange (especially a foreign bill of exchange)