OAuth 2.0 is an open standard for authorization and works over HTTPS. In Setu's context, it is used to authorize API requests with access tokens. Read more about OAuth 2.0 here ↗.
For Setu products, OAuth keys provide a lot of flexibility—you can set up a single set of keys to authorize requests for multiple product configurations or authorize requests for a single configuration using multiple sets of keys. One can delete/regenerate OAuth 2.0 keys. These features are not available for JWT.