'update-grub2' is a symbolic link to 'update-grub': $ ls -l /usr/sbin/update-grub2lrwxrwxrwx 1 root root 11 juil. 8 08:09 /usr/sbin/update-grub2 -> update-grub
Calling one command or the other leads to executing the exact same program. No difference whatsoever.
