1.   Eyepiece Projection or Afocal:   With eyepiece projection you simply use a digital camera to take a photo through the eyepiece of the telescope.  Your photo will be essential the same as what you see if you were looking through the telescope.

2.  Prime Focus:  In prime focus photography you must use a "Single Lens Reflex" camera, commonly called an "SLR" or "DSLR" for "Digital Single Lens Reflex."   A SLR has been popular for years and is the type of camera with interchangeable lenses where you are looking through the lens of the camera when you are looking through the rangefinder.  In prime focus photography you remove the lens from the SLR and remove the eyepiece from the telescope.   Then you connect the camera and telescope so the telescope essentially becomes a larger telephoto lens for the camera.