AWS Region and AZ, Availability Zone

Region 
is a cluster of data centers and AWS has Regions all around the world.
Region is a collection of AZs, Available Zones (usually 3, min =2 and max=6 )
Most AWS services are region scoped.
Region name can be us-east-1 , us-west-3

AZ , Availability Zone

• Collection of discrete data centers with redundant power,network,connectivity.
• Separate from each other -> isolate from disaster.
• Connected with -> High bandwidth , Ultra low latency
• Name can be  ex:  ap-southeast-2a, ap=southeast-2b, ap-southeast-2c

For more

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