Yes, they are different! And, no you do not peen regular plugs to lock them in place. The front and rear plugs are simple disks with no perimeter flange. Because of this design, they are a relatively loose fit until you indent the center to lock them in place.
I think the only way to get the plugs from most of the venders is to purchase the entire set. Usually, the rear camshaft plug is not included in the set.
