to be "headlight junkie" correct, a retrofit is taking out the halogen projector and swapping in the correct HID/LED projector. This is the correct way to run HID/LED setups.
Changing bulbs is not a retrofit of any sort, it's just adding PNP (Plug and Play) HID/LED bulbs into housing. adding PNP HIDs to a Halogen projector gives you average results. nowhere near as bad as stuffing them into basic Halogen reflective housings. contrary to what your eyes thing they see, when you add PNP HID/LED to Halogen lights it creates more foreground lighting, which makes your eyes/brain think they are better. Yes, they are brighter but your Halogen bulb had more USABLE light. For example, everyone's eyes are different and everyone wears different glasses. Well, your headlight bulbs are your eyes and the projectors are the glasses, each one is designed for the correct bulb to work "properly." When taking pics of a retrofit you should be able to see the cutoff beam. A PNP kit cannot mimic this.