i have installed rhel5 quite many times.......
when i see grub.conf after installation, somtimes "kernel /boot/vmlinuz-2.6.18-8.el5 ro=LABEL=/ rhgb quiet" will be there or "kernel /boot/vmlinuz-2.6.18-8.el5 ro=LABEL=/1 rhgb quiet" will be there................
what is the significance of label=/ or label=/1 ? ? ?......what is the reason for this differnce(label=/ and label=/1).......
No significance. 
I think it is a stupid thing to use "/" and "/1" here because it causes confusion. They are just labels, same as anything like "myroot".
Use the command "e2label" on your root devices, you'll see one is "/", one "/1". The label can be used in substitution of the normal device name, like in /etc/fstab.