MOTM

In reading about the white, ... noise generation of the MOTM 101 and the
Oakley noise module, I noticed that the audio noise generation is
implemented in different ways: the MOTM 101 uses zener diodes and the
Oakley uses an npn transistor.

Are there any differences in the audio (or other aspects) of these  2
implementations? 

[Note: I'm not interested in comparisons of these 2 *modules*, just that
they have implemented noise in apparently different ways]
Thanks, Jeff