Well here is a fine example of both. The longer ones are from the spinal area, down to the rib and comes out as a whole piece (if cut right) usually about 2 ft long. These have always been referred to as back straps.

The two smaller pieces in the middle are the loins, and can only be cut from inside carcass towards the back. They are very distnctive looking, and very tastyas well. No need to even soak or refrigerate...just put in a pan of butter, garlic and lemon pepper and barely cook...it will melt in your mouth!