Switch and router

Here is an excerpt from a Cisco paper on Layer 3 switching, Layer 3 Switching Demystified:

In discussions about Layer 3 switches, often the prime area of focus is raw performance which refers to the aggregate number of packets that a device can switch in and out over a fixed period of time. Layer 3 switches tend to have packet switching throughputs in the millions of packets per second (pps), while traditional general-purpose routers have evolved from the 100,000 pps range to over a million pps. In essence, aggregate performance is the primary difference between Layer 3 switches and traditional routers. The features and functionality of Layer 3 switches and routers do, however, have numerous similarities. These similarities manifest themselves not only in packet switching methods, but also in the categories of route processing and intelligent network services. All three of these categories are explained further in the remaining sections.

The paper can be found here:
http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm