2000ttownexpy, projector headlights are easily identifiable by the small round lens in front of where the low beam light comes out. Like JT said, there are good ones, there are bad ones. The idea behind a projector setup is that you are putting a lens in front of the light to help "focus" the light on the road and not allow it to spread to the side of the road. This gives you more light when looking straight down the road. But, as you are probably thinking, if the light is being focused straight down the road, then how do I see the side of the road. There is the issue. You will still get some light on the side of the road, but not what you are used to at the moment.
Keep in mind that any time you put something in front of the headlight bulb, you are reducing the amount of light that is making it on to the ground (nothing transmits 100% light with no losses). If you look at these lenses, they can be fairly thick. More material, more losses. But, they are desirable because of bringing the light that is "lost" to the side of the road back to the road.
Also keep in mind that to have a "focused beam of light", you need to have the filament of the bulb and the lens a finite distance apart. You don't have the correct distance, the light is not focused and therefore you are tossing the light who knows where. Read this as "majority of it not going straight in front of the truck". This is where the cheapy projector headlights have their issues. Another one of the "you get what you pay for" items.
if you want more info on this, let me know. I will try to keep the technical stuff out of the conversation and explain it more in layman's terms.
