Virtual Tunnel Interfaces (VTI) are used in route-based VPNs. VTIs allow for the establishment of a tunnel that routes traffic based on the routing table rather than individual security policies. This makes route-based VPNs more flexible and easier to manage when compared to policy-based VPNs. SSL-based VPNs, on the other hand, do not use VTIs, as they rely on SSL/TLS protocols to secure the traffic rather than creating virtual interfaces for routing.