IP virtual servers (IPVS) are almost identical in purpose and use to web switches, the difference being only that they aren't specifically a piece of networking hardware. Instead, they are components that run on traditional (often commodity) servers and employ either a user space application, modified IP stack, or a combination of the two to provide a distribution point for IP traffic. By exposing a single virtual IP address for a service and distributing the traffic across a configured set of private machines, IPVS accomplishes the task of load balancing inbound traffic.
From a network topology perspective, a configuration using IPVS looks identical to a configuration based on web switches. Aside from the fact that web switches typically have several Ethernet ports to which servers can be connected and generally higher performance metrics, there is little difference between the placement and operation of IP virtual servers and web switches.