Is there any difference between a Power Distribution Unit (PDU) and a Remote Power Panel (RPP) in context of data center? If yes, then what is it?. Thanks.

A PDU usually contains an isolation K rated transformer, several branch circuit panelboards, and monitoring and surge suppression equipment, popular in data center and IT rooms.

An RPP will be nothing more than a panelboard or two in a matching enclosure designed the same as the PDU.