RPC vs. API

• -| RPC: Remote Procedure Call
• RPC: a client invokes a function on a remote server (as if it were local).
• RPC: Protocols; XML-RPC (WordPress uses it), JSON-RPC, DCOM, RMI, and CORBA
• -| API: Application Programming Interface
• API: A set of rules and specifications to define how the interactions should work.
• API: Can expose; web services, libraries, and frameworks
• API: Protocols and formats; HTTP, REST, SOAP, GraphQL, XML, JSON, etc.
• -| The difference is on the level of abstraction.
• RPC: Low-Level, very close to the implementation (the clients know the signature)
• API: High-Level, away from the implementation (the client only needs endpoints and API Parameters)
• RPC: highly coupled; changes to the implementation have a high impact.
• API: loosely coupled; changes to the implementation have a low impact.
• RPC  is more efficient and faster. Uses binary formats
• API: can be complex and slower. Usually more textual.