Some basic comparision would be:

Data schema: gRPC uses a schema to define the structure of the data being transmitted, while REST does not. This means that gRPC has the ability to enforce a strict structure on the data being transmitted, while REST relies on documentation or other out-of-band methods to define the structure.

API design: gRPC uses a service-based API design, where the API is defined using a service definition in a .proto file. This file defines the service and the methods that can be called on the service, along with the request and response types for each method. In contrast, REST uses a resource-based API design, where the API is made up of a set of resources that can be manipulated using HTTP verbs (such as GET, POST, PUT, etc.).

Performance: gRPC can be faster than REST due to its more efficient encoding and the use of binary data transfer. However, the performance difference may not be significant in all cases, and other factors such as network latency and server-side processing can also impact overall performance.

Overall, gRPC and REST are both viable approaches for building distributed systems and APIs, and which one is the best choice will depend on the specific needs of your application.