The overhead garage door frame is constructed with 1-1/2” LVL (laminated veneer lumber) for its stability and strength. Each sections meeting rail has a 1/4” shiplap joint to act as a weather blockade. The frame rails and stiles are joined with mortise and tenon joinery along with type 3 waterproof glue.
The backside of the garage door frames, or what is visible from the inside of your garage is a clear stain grade 1/4” exterior grade mahogany plywood that creates a finished look.
Popular choices are quarter sawn sapele mahogany, Sipo mahogany, clear vertical grain western red cedar, clear vertical grain Douglas fir, Spanish cedar and Armorite. For painted doors I’d recommend Tricoya and Armorite composites.
The overlay is the trim around the door and windows. Endless designs are available for the layout of the overlay. My typical overlay edge profile is a 1/2” radius thumbnail. Many other profiles are available. There are no visible fasteners or plugs used on stain grade doors