I know it is a stupid question, but I really wanna figure this out. The thing is that I have met someone want to buy bulbs, he want "Edison" style bulbs (traditional bulbs), not PAR bulbs. So what's the difference between Edison style bulbs and PAR bulbs? I guess all "Edison" style bulbs are transparent, able to see the fuse clearly. Am I right? If my expression is unclear, please indicate.
To me Edison style bulbs are what are formally designated as Type A, roughly spherical with a cylindrical neck and screw base. Traditionally seen in table and floor lamps with shades and in fixtures that either expose the whole bulb or have a crude reflector behind the bulb.
PAR, on the other hand, are roughly conical, with a rounded or flat face as the based of the cone and a very good reflective surface on the cone portion.
More specifically PAR stands for Parabolic Aluminized Reflector. The parabolic part means that the reflector will take all light rays striking it from a filament located at the focal point and send them out directly along the axis of the bulb.
In a recessed fixture an A type bulb will loose much of its light output to the collar on the inside of the fixture and will give a very wide light distribution. A PAR bulb will send most of its light directly out of the fixture at an angle which will depend on the nominal angle of the bulb, ranging from spot through narrow flood to wide flood.
In newer lighting design terminology an "antique" Edison bulb is clear with a long visible reddish-yellow filament, looking like the carbon filament in the earliest bulbs invented by Thomas Edison. Other type A bulbs may be frosted or otherwise hide the filament to give a softer light distribution. And give a much whiter light.
You need to find out which meaning of the term your customer is using.
