Glossary
A system runs in several geographic regions, so the failure of one region does not end the service, and users have shorter distances.
Multi-region is two different goals in one word: resilience and proximity. Proximity is often served by an edge cache. Resilience requires state to travel, and that is where it becomes expensive.
The decisive question is whether a failover happens automatically or whether a person decides. Both are defensible, but only one of them works at three in the morning without a phone call.