QUOTE(Sycoarkantos @ Jul 31 2007, 12:07 AM)

You mean like:
|---|+--- - |---|
|``````````|
|------(X)------|
|``````````|
|------(X)------|
that?
If you mean voltage difference as in something like a power source, then no, the light from each one would remain the same, since the source is providing the same amount of energy to each light bulb as they would if there is one, just in a lower rate per second
If I didn't answer your q, then sorry.

Would the brightness of one lightbulb in a circuit be greater than the brightness of one of the two lighbulbs in a circuit?
QUOTE
The bulb will only supply a certain amount of resistance, and draw so energy from the source, so they should be the same in brightness. If the battery and wall source supply the same amount/rate of energy then it shouldnt make a difference. Cant really say though, it all really just depends on the current situation in question.
I don't think you know what you're talking about. That or you don't understand the question.