Gateway types
Vpn - To send encrypted traffic across the public Internet, you use the gateway type 'Vpn'. This type of gateway is also referred to as a VPN gateway. Site-to-Site, Point-to-Site, and VNet-to-VNet connections all use a VPN gateway.
ExpressRoute - To send network traffic on a private connection, you use the gateway type 'ExpressRoute'. This type of gateway is also referred to as an ExpressRoute gateway and is used when configuring ExpressRoute.
Each virtual network can have only one virtual network gateway per gateway type. For example, you can have one virtual network gateway that uses -GatewayType Vpn, and one that uses -GatewayType ExpressRoute.
Azure ExpressRoute creates a private link between on-premises infrastructure and Azure, offering more bandwidth, reduced latency, and higher security, but it is typically more expensive and requires additional configuration.
On the other hand, Azure VPN Gateway establishes a secure VPN over the public internet, making it a suitable choice for small to medium-sized enterprises that require secure access to Azure without the resources for a dedicated private connection.