Nope. CentOS is just a more "server-oriented" distribution which strips out a lot of the user/desktop fluff by default which Ubuntu is more desktop oriented by default. CentOS is a bit leaner. Other than that, Linux is Linux, you can do just about the same things no matter what distro you choose.
There is a Ubuntu-Server edition that matches CentOS in this regards. http://www.ubuntu.com/download/server