Think of it in the sense of enterprise-class equipment.

Routers usually have a single WAN port, a console serial port, an uplink port, and an auxilliary serial port, and that's about it. It routes by TCP/IP.

Switches have one uplink port, and a whole lot-o-traffic ports. It routes by MAC address.

With the Linksys router, the routing functions are combined with 1, 4, 8, or 16 traffic ports. It's not a switch by software/firmware, but by appearance and function it is, using TCP/IP to route over multiple ports.