A region is a geographic area (e.g., `eu-central-1`) that contains multiple Availability Zones. An AZ is a physically separate data center (or group of them) within a region. Spreading across AZs improves availability; spreading across regions improves geo‑redundancy.
Expanding on the short answer — what usually matters in practice:
A tiny example (an explanation template):
// Example: discuss trade-offs for "region-vs-availability-zone:-what’s-the-differen"
function explain() {
// Start from the core idea:
// A region is a geographic area (e.g., `eu-central-1`) that contains multiple Availability Z
}