The hub is the part that the wheel bolts to and is the same for all SHOs and SLOs (as well as Sables and certain Continentals). The knuckle is the part that the caliper, strut, control arm, tie-rod end, ect bolt to and are different depending on year. When you get knuckles from the boneyard they will come with hubs since they are pressed in.
As for the ABS sensor, be very careful with the ABS sensor! It is quite fragile. The housing is plastic and the sensor that points at the ABS ring is thin aluminum. After removing the retaining bolt, GENTLY twist the housing with pliers. If the aluminum sensor doesnt turn with it, stop. You will have to press it out. About half that I have done had to be pressed. I use a small gear puller and a flat piece of steel between the sensor and the center bolt of the puller.