Webupon

Mozilla Firefox 2.0 and Netscape 9.0 are virtually identical (including source code) except for Netscape’s theme (packaged for Firefox at https://addons.mozilla.org/en-US/firefox/addon/4784 ) and integration of Propeller.com, a social-news site (available as the Firefox addons https://addons.mozilla.org/en-US/firefox/addon/4033 and https://addons.mozilla.org/en-US/firefox/addon/4034).

Bottom line: There is practically no difference.

But if you want a fast browser, then you should look at the following options.

K-Meleon

SeaMonkey

And always remember about skins and themes. K-Meleon skins are avaliable here

while here is a link to Seamonkey.