Well, to put it simply, yes, that is, that's the easy answer.

But more accurately, in 4WD (HI or LO) engine power is equally distributed to the front and rear driveshafts. If all 4 tires have equal traction then engine power is evenly distributed. With open differentials in the front and rear, engine power is sent to the wheel with the least traction. In other words, if you have one front tire in the air and one rear tire in the air, you're not going anywhere. (And now we move on to the "limited slip differential" discusson.)