An availability zone isn't equivalent to a data center, as it might consist of multiple data centers. A better explanation for availability zone would be "a bunch of data centers in close physical proximity, exposed to users as a single logical entity".
Or as AWS explains it [1]:
> An Availability Zone (AZ) is one or more discrete data centers with redundant power, networking, and connectivity in an AWS Region. AZ’s give customers the ability to operate production applications and databases that are more highly available, fault tolerant, and scalable than would be possible from a single data center.
Or as AWS explains it [1]:
> An Availability Zone (AZ) is one or more discrete data centers with redundant power, networking, and connectivity in an AWS Region. AZ’s give customers the ability to operate production applications and databases that are more highly available, fault tolerant, and scalable than would be possible from a single data center.
[1]: https://aws.amazon.com/about-aws/global-infrastructure/regio...