As you know, A VPN creates a secure,encrypted connection between a user’s computer and a server. This allows the user to access resources anonymously and securely, without fear of snooping or hacking. In other words, VPNs work by creating some sort of perimeter around assets or activities within a network. Users who have permission to access the VPN are the only ones who can access any resource in the perimeter. This limited access is what essentially secures the network. The VPN model therefore assumes that whatever is allowed to pass through the boundaries of the perimeter can be trusted, since it has permission to access the VPN. This can be risky.
The zero trust model throws out the perimeter and instead works by verifying each user trying to access any resource within the network. By doing so, it protects the entire network. In other words it's no longer about trusting anyone who is inside the network, which is what traditional VPNs do. Zero trust grants access based on identity, and this is done continuously. So a user can be granted access today but be denied tomorrow. This model also goes further to define what a user can do and in what context.