/etc/localtime is a symlink.
/etc/sysconfig/clock is a config file.
Q: What is the difference between them? Each could store timezone setting.
Using SLES.
/etc/sysconfig/clock is a config file used to symlink /etc/localtime correctly. If you run rpm -q --scripts timezone you can see the timezone package will automatically create that symlink for you if it isn't there.
I can tell you in the Red Hat land of stuff, it doesn't use a symlink and some other packages (like glibc) will use the setting in /etc/sysconfig/clock to copy the appropriate /usr/share/zone/foo/bar file to /etc/localtime . I'm not sure if Suse has anything similar.