Something that may be causing confusion is that some versions of the atmega328 have two additional analog ports, A6 and A7, that are not usable as digital pins. The UNO does not have these additional ports because the physical package does not have enough pins (although the ports still exist internally on the chip itself).
Another confusing thing is that analogRead() will accept either the Ax pin name, or just x, because the function only works on analog pins, but all other port functions assume x refers to a digital pin.