I recently started using RHEL-Like distros on my daily-use desktop. (because they are really stable).
Started with CentOS, then moved to Scientific Linux... and then decided to give Oracle Linux a try (even if it's aimed at servers, the install DVD has a "Desktop" option.)
The 6.3 release ships with the standard linux kernel and UEK2.
Are there any noticeable differences between these two kernels for daily desktop use?
Your Desktop use is probably different from mine or the desktop use of someone else.
I suggest to read the following:
Keep in mind though that RHEL and Oracle Linux UEK based kernels are designed for server use and server hardware. Your mileage with sophisticated desktop, mobile or advanced consumer grade hardware will vary.