REST (JSON over HTTP) is easy to debug and widely compatible. gRPC uses HTTP/2 + Protobuf, gives strong contracts, good performance, and supports streaming, but is harder to inspect without tooling and is less browser-friendly. Pick based on interoperability, performance needs, and team/tooling maturity.
Expanding on the short answer — what usually matters in practice:
A tiny example (an explanation template):
// Example: discuss trade-offs for "rest-vs-grpc-for-service-to-service-calls:-what-"
function explain() {
// Start from the core idea:
// REST (JSON over HTTP) is easy to debug and widely compatible. gRPC uses HTTP/2 + Protobuf,
}