The first method uses a torque rod that connects the two halves together. See my drawing which I will post shortly (after I draw it).

The second method uses a pair of pushrods that are joined together near the servo in the servo tray under the wing. Depending on how you do that, you would use either a pair of metal pushrods that are either joined together with silver solder or using wheel collars and a set screw... you push the ends of both rods together with one longer than the other, then slide the collar over both and tighten it down.

There is also the method that uses a pair of servos in the rear of the fuselage, one on the right and one on the left, each has it's own pushrod connecting to it's horn on the elevator.

The first method is used on smaller aircraft, trainers, and so on, that don't have as much stress back at the elevator when maneuvering. And, you cannot adjust them separately unless you bend the torque rod, difficult when all is installed.

With two pushrods, you can adjust each half individually for straight tracking of the aircraft. And, of course, the same follows with two servos, one on each elevator half.

I have all three. I have a club trainer that has the torque rod, three other aircraft, one sport and two pattern types with pushrods joined in the third method in the drawing, and another aircraft with a pair of servos back aft. I'm sure some others will have more pros and cons of each method, but if your plane comes with torque rods, you can do either the torque rod method or leave it off and control each half separately. It just takes the additional control rod from the servo and some additional work to get it installed.

CGr.