Precium exposes two systems. Which one you integrate against depends on what you are collecting, not on which product name you were sold.
Products
One API, two products
Server-to-Server and Payment Orchestration are two documentation sets over one API. Both call the card gateway, and both resolve against the same specification, which is why there is a single card API reference rather than one per product.
The Direct Debit order API is a separate system on its own base URL, with its own authentication. Its different path convention is by design, not an inconsistency.
Easy to miss and worth stating plainly: debit order payment methods also appear
in the ordinary checkout flow, as debicheck and eft in
payment_method_whitelist on a normal purchase. So debit orders have a shallow
route through orchestration and a full mandate lifecycle route through the Direct
Debit API, and they are not the same integration.