Azure's central networking point that connects multiple networks, branch offices, and VPN connections. Like a grand central station for network traffic - all routes converge here and get directed to their destinations.
A global corporation uses Virtual WAN Hub to connect 100+ branch offices worldwide to their Azure resources through a single, managed hub.
All are hub-and-spoke connectivity services that centralize routing between multiple networks (VPC/VNet), on-prem sites, and VPN/SD-WAN. Azure Virtual WAN hub is the managed hub inside Virtual WAN; AWS Transit Gateway is the routing hub for VPCs and VPN/Direct Connect; GCP Network Connectivity Center provides a centralized connectivity management plane (often using Cloud Router/VPN/Interconnect as data-plane); OCI Cloud Router provides dynamic routing for attachments such as VPN and FastConnect.