Technically, white
noise is a very
specific kind of noise: If you hook a source up to a
spectrum analyzer, you should see that all
frequencies are
equally represented in
power. Usually, what you get on your
TV or your
storage media will be overrepresented in some
bandwidth, most likely 60Hz.
White noise is good for getting a quick and dirty plot of frequency response of any circuit: Just put your generator at the input, and feed the output into a spectrum analyzer....On a log-log scale, it should look like the amplitude measurement of a Bode plot.