[CentOS] Thunderbird and Firefox 10 font rendering

I use both 3.6.26 (from centOS 5) and 10.0.2 (binary from mozilla).
And, after setting the same font settings in both, I cannot see any real differences...
Only tiny difference I could find if I screenshot both and zoom a lot is lighter pixels in the anti-aliasing of 10.x.
But that might just depend on the position in the display maybe...

JD