Hanger alignment isn't the issue. Dropout position and alignment is. Once it's pulled apart the repair would call for a fixture to ensure that the new dropout is in the right place, especially the height and parallelism to it's mate so the rear wheel will be square.

If it's left in place, position can be established by closing the break properly.

The difference is that the quick repair is straight torch work and can be done by just about anybody, like a car, motorcycle or farm tool mechanic, and the second calls for some framebuilding skills. It's also the difference a quick and cheap job, and something that might cost more than the frame justifies.