To me rooting and unlocking are two very different operations. Unlocking = removing carrier restrictions placed on the tablet while Rooting means "formatting" and installing a newer or better operating system??
Rooting "unlocks" your device in the sense that you install custom recovery software (e.g., ClockworkMod or TWRP) and have root access (i.e., you can access *all* files). Rooting then allows you to flash a custom ROM. You can also root the device, stop there, and apply no further changes. Everything would be the same, then, except that you would also be able to access all the files on the system.
But yes, I do believe that removing carrier restrictions is something different altogether.