The only difference I can think of is the administrative 
tools.
Redhat uses Redhat-config-xxxx
and Suse uses Yast. Personally I prefer Yast because it has 
more modules. However, both tools configure the same things 
and modify the same files. If you use a tool like webmin or 
Linuxconf, you won't see a bit of difference between the 
two distros.

I use the Redhat Linux 8.0 Bible as my main reference, and 
its instructions apply to the several different Linuxes I'm 
using (more or less).

As Rick said, your main interface will be Gnome or KDE and 
the only differences you'll see there is that SuSE provides 
prettier eye candy (out of the box) than Redhat.

For software update, Redhat is using up2date or Yum like
utilities
For same purpose Suse is using Yast / Yast2

Red Hat Linux  is a product of  Red Hat 
 SuSE Linux is a product of Novell 


Upto  to Version 10 suse is  using ReiserFS  as default
Filesystem.Now they changed to ext3 as default one.

Redhat is coming with ext3 or ext2(before rhel 3 )as default
file system