I think the main difference is the expectation that you start signalling, if appropriate, before joining the roundabout. My main complaint (OK one of my main complaints) is that drivers turning right start signalling right and then forget to signal left as they leave...
Might be a regionalism, but here in Oregon, we don't signal going in, but signal right before we intend to exit. That way the next incoming driver can enter the roundabout and keep traffic flowing. We have a LOT of roundabouts though, like dozens upon dozens, and many of them are over saturated. It may be a local response to the traffic patterns here, not sure.
The most important thing is for everyone to speak the same protocol, provided that the protocol meets some minimum standard of fitness-for-purpose. But… yeah, I think you're doing it wrong.
