CBS doesn't carry the same brand name in the sports world that ESPN does. CBS is the "most-watched cable network" but not because of sports. Shows like Hawaii Five-O and How I Met Your Mother bring viewers to CBS on a regular basis more than the occasional afternoon NFL game.
The only exception is during late March and early April, when CBS owns the sporting world with exclusive rights to March Madness. During that month, CBS pushes their sports coverage hard, but for a fan like me, who lives for ESPN and ESPN.com, the network disappears from my consciousness for a while, especially during the summer.
However, compared to second-tier sports websites like NBC Sports and Yahoo! Sports, CBS has a pretty stellar website design. They use a similar running score ticker at the top of the site to ESPN's, and they have an eerily similar overall layout, with some things reversed.
For example, the five window design ESPN has at the bottom of their main page is much like the three tabs that CBS runs above their lead main page photo. Moreover, their headlines run down the right side of the page in the same way that ESPN's do. They also have a fan poll on the page, but it is located higher up than ESPN's.
As far as differences go, CBS's front page isn't nearly as long as ESPN's. I'm still not sure whether that's a good or a bad thing. CBS also doesn't have NHL or Nascar on top of their site, instead listing Tennis and High School before the More Sports tab. It shows a difference of opinions between the two organizations on which sports will attract more clicks on their respective pages.
Lastly, CBS seems to have a smaller, more "journalistic" writing staff than ESPN does. ESPN is a huge site with hundreds of writers covering thousands of different topics. CBS's writing staff covers less information and try and present it in an extremely professional manner.
Overall, no site could possibly divorce me from my lover, ESPN. But CBS Sports does present a quick and concise way of getting information about the most pressing issues in the world of sports.