Yes! Correct! There is no…
Yes! Correct! There is no true 4-wheel drive vehicle unless you have a locking differential which is rare for most "4x4" or "AWD" vehicles. A basic 4x4 (AWD) vehicle (without a locking differential) only utilizes one tire in the front and one tire in the back.
I have to mention, and I am not certain about this, but apparently, Subaru's X-mode will utilize a braking system for whichever tire is needed to boost the grip of one that might be spinning. That's pretty dang cool. But again, it is not a true 4x4 (AWD) system, like most "4x4" trucks etc.