Using the Orders or Shipment object to purchase labels?

You could use the Orders object exclusively instead of creating a Shipment object, but it's not recommended for a few reasons.

1. Shipment options and customs information must be specified using the Shipment object, not the Orders object.
2. UPS will tie all of their rates and trackers to the first Shipment in the Order. It'll be difficult to glean tracking and rate information from UPS without creating a Shipment.
3. EasyPost Insurance is handled on the Shipment level, not the Order level.