is there a difference between these lines in `/etc/apt/sources.list`?

In a guide for installing a wireless card, I'm told to add the following lines to /etc/apt/sources.list:

deb http://http.debian.net/debian/ wheezy main contrib non-free

This is what my sources.list file already looks like (skipping the residual commented out line from the CD installer):

deb http://ftp.us.debian.org/debian/ wheezy main
deb-src http://ftp.us.debian.org/debian/ wheezy main

deb http://security.debian.org/ wheezy/updates main
deb-src http://security.debian.org/ wheezy/updates main

# wheezy-updates, previously known as 'volatile'
deb http://ftp.us.debian.org/debian/ wheezy-updates main
deb-src http://ftp.us.debian.org/debian/ wheezy-updates main

Keeping in mind that the wiki article may be several years older than the current Debian version, my question is, are http.debian.net and ftp.us.debian.org different, or will both URLs retrieve the same packages?

If they are basically the same, instead of adding an additional line of the config file, should I instead edit the first line to this? or will that give me incorrect packages?

deb http://ftp.us.debian.org/debian/ wheezy main contrib non-free