Region

In Azure

A set of data centres deployed within a defined perimeter and connected through a dedicated  low-latency network. Azure has 42 Regions Available and 12 more announced as of August 2018 .

 

 

In AWS

A region provides multiple, physically separated and isolated Availability Zones which are connected with low latency, high throughput, and highly redundant networking. AWS provides 18 Regions with four more announced as of August 2018.

In essence they’re the same in both Clouds.

References:

https://aws.amazon.com/about-aws/global-infrastructure/

https://azure.microsoft.com/en-au/global-infrastructure/regions/

https://azure.microsoft.com/en-au/global-infrastructure/geographies/

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.RegionsAndAvailabilityZones.html

https://aws.amazon.com/about-aws/global-infrastructure/