PSP moves money from Buyer(through Issuing Bank) to Merchant(through acquiring bank)
It handles both the technical and financial parts.
payment gateway does only the verification and transmission to the PSP.
Reliability
Business
- Reconciliation
- Payment Status
- Handle Delays
Technical
- Redundancy
- Persistent Quuues
- Retry Strategies
- Idempotency
- Fault Tolerance