[CentOS] RHEL / CentOS Kernel Updates

How are the updated kernels released by Red Hat / Cent OS related to
the latest vanilla kernels ? Are the changes, new features and
drivers, etc. available in the newer kernels also ported to the
updated kernels released by Red Hat in their entirety ?

For the lifetime of a distribution like RHEL 4 or RHEL 5, Red Hat
would stick to the same major and minor number of the kernel and would
just change release numbers. What  is the relation, if any, between
the new kernels and the updates released by Red Hat ?

Thanks,
-- 
Manish Kathuria
Tux Technologies
http://www.tuxtechnologies.co.in/