EC2 Local Zones

The advantage of local zones are that they bring the AWS resources (such as EC2 compute instances and RDS databases) closer to your users, so resources can be accessed with much lower latency.

The disadvantage is that it's usually a cut-down subset of what's available in a region, e.g. to continue the EC2 example there are far fewer instance types available.

Features that illustrate all of these points (and more) are here https://aws.amazon.com/about-aws/global-infrastructure/localzones/features/

The FAQ tab here is useful as well https://aws.amazon.com/about-aws/global-infrastructure/localzones/faqs/