Open banking is the broader concept: securely sharing bank account data with third-party providers through APIs, with the customer's consent. PSD2 (Revised Payment Services Directive) is the EU legislation that implements and regulates open banking in the European Economic Area. So PSD2 is one way—the EU way—of doing open banking; open banking itself is global and can be driven by other regulations (e.g. UK Open Banking Standard) or industry standards (e.g. FDX in the US).

Under PSD2, banks in the EEA must provide dedicated access to licensed AISPs and PISPs. The UK kept equivalent requirements after Brexit. Other regions (Australia, Brazil, etc.) have their own open banking or open finance frameworks. The Open Banking Tracker covers both PSD2 and other open banking regulations worldwide.