I know that fog lights have a wider shorter light pattern and a driving light has a narrower longer pattern but why?? Is it the shape of the reflector or the bulb itself?? Or a combo of both??

I did do a quick search here and google but all i kept getting is the differance in patterns with no explaination

thanks in advance for any info on this

 

The shape of the reflectors is the difference. Most use the same bulb.

Example:

Hella 500 (55W H3 bulb):



and Hella 500FF (same bulb):