[Hampshire] Kernel Memory Models

I was at a presentation today where the speaker said that one of the
differences between SLES & RHEL was that they use a different way to
allocate memory.
He said that SLES uses a NUMA model whereas RHEL uses a 'flat' model.
He indicated that the NUMA model gave a slightly better performance that
that used by RHEL. This was observd in a DB Benchmark test. TPC-H

Can anyone verify this statement?
What do other stock kernels use and can the NUMA model be enable of a
RHEL Kernel?

Stephen D