An order must always have a billing period and a price period. The billing period is how the invoice will be billed (invoiced).
Supported use cases for billing periods are Annual, bi-annual, quarterly, monthly, and end-of-term.
Supported use cases for price periods are Annual, quarterly, and monthly.
Price period is how your prices are communicated to customers. In standard cases with annual recurring fees, the price period does not affect billing. For usage-based charges, the price period cannot be longer than the billing period.