kernel on installation dvd of linux distributions

i copied the kernel and initrd from installation DVD of Red Hat
to my boot folder
#cp Red-Hat-DVD-i386.iso/boot/i386/loader/vmlinuz /boot/
#cp Red-HatDVD--i386.iso/boot/i386/loader/initrd /boot/

and copied the ISO image of Suse DVD on a partition on hard disk that
was completely free

now I booted from kernel image that was copied by the above commands
then I got the graphical installer screen asking me to start
installation
by this method I have been able to install Red Hat in a friends comp
without using CDROM or DVD ROM

what I want to know is if instead of the kernel image and initrd image
that are on the installation DVD if I put up the kernel image and
initrd that already are existing on a system
i.e.
vmlinuz-2.6.18.2-34-default
and initrd-2.6.18.2-34-default

the system does not begin installation

infact it boots into the new kernel on the system.

My question is what is the difference between the kernel images that
are on the installation media inside Red Hat-DVD-i386.iso/boot/i386/
loader/
(name vmlinuz and initrd )

and the kernel images that are on the system after a fresh
installation has taken place inside /boot/ folder
which was able to boot the system instead of starting installation