Firefox has lower memory usage.
Load times are about average for every web page on both browsers, both startup and webpage loading.
Firefox supports sandboxing, which will run in a seperate plugin container when needed.
Firefox has equal W3C standards support.
Firefox has equal WebGL and GPU support.
Sorry, it appears that Firefox 4 does have less memory usage.
I installed Firefox 4 after checking out some youtube videos with comparisons of the browsers and got these results:
Google Chrome 10 loads significantly faster.
Firefox 4 does not support sandboxing, except for an add-on on OSX.
Firefox 4 WebGL is very badly implemented and uses DirectX if I recall. It runs at 20fps less for me, even worse some times. Although my WebGL mysteriously stopped working for all browsers.
Standards testing using
http://html5test.com/240
and 9 bonus points
for Firefox
278
and 13 bonus points
for Google Chrome