What is the difference between a payment gateway and an UPI?

A payment gateway is an intermediary platform that securely processes online transactions, managing various payment options like cards and UPI. It handles encryption, authentication, and reconciliation. UPI (Unified Payments Interface) is a real-time payment system developed by NPCI that facilitates instant inter-bank transfers using a single mobile application. Essentially, a payment gateway is the platform, and UPI is one of the payment methods it can support.