soft or diffuse?

[clickcanon40]

Is there much of a difference between one of the flash diffuser caps or a small soft box on your flash?

If so what are the differences and which do you find the most useful to use on a regular basis?

I'm going to order one or the other with my 580ex II

[doidinho]

The diffuser cap is a move toward making your flash more like a bare bulb, throwing light in all directions. This is good four bouncing if you have walls and ceilings as you effectively get a very large light source. It's not so good outside as the light that would be bounced indoors is lost. A softbox actually turns you flash into a larger light source and will work great inside and out. A softbox will also give you larger catch lights and specular highlights as well.

How arere you going to be using your flash; on or off camera? What type of shots are you planning on taking? These will help answer the question of which would be better for you.