That's correct. A BAPI that is set-up according to the BAPI design specifications always returns a RETURN parameter. In older BAPIs, it returns a structure of type BAPIRETURN, but in newer BAPIs, it either returns a structure or table of type BAPIRET2.
Do note that it is not enforced in SAP/ABAP to build BAPIs this way. You may run into esp. custom BAPIs that are not following these guidelines and don't return the RETURN parameter.