Location, Regional & Global
AWS is a global cloud provider. As of 8/2018 there are 55 AZs, and 18 geographic regions. The term region is used to describe a geographic region. The US-EAST region has two regions: North Virginia, and Ohio. These two regions have nothing to do with each other beyond their proximity. When discussing high-availability, failover, and co-location we need to be very specific. A region is broken down into availability zones. Having your infrastructure in more than one AZ in the same region should be considered high-availability and having a failover but not co-location.
An AZ may be broken up into many different data centers. This is worth noting that due to the fact you have no control over the data center of your infrastructure network latency when dealing with high volume may be noticable within a single AZ. AWS does not deal with anything more specific than the AZ.
Global Services
Almost all services are regional specific except for the following:
Keep in mind that the dreaded eventually consistent data model is applicable to these global services. This is an important thing to remember, especially with IAM roles and policies. The biggest challenge with the eventually consistent is not being able to know whether or not the change has propagated or not.