They are bu**ers to get out, I use a small pair of mole grips from the side to crack them, then undo with a screwdriver.
Refitting with little allen head bolts, 6p each from the local Ironmongers.
I have measured both today, and the dimensions and reach are the same with both, they are a perfect interchangable fit and the electric sockets are the same.
The difference could be the power of the solenoid, or Mr. T. just getting frisky with part numbers, stick it on and see.
Also maybe there will be a sparky minded member who could tell you how to test for this.