As a young person, the history behind those names seems incredibly baffling
(or stupid, not sure which). People have wondered about it before; you
might search Google Groops to try to make sense of it yourself.
Regardless though, Vcc refers to a common positive supply of bipolar ICs (no
doubt related to a collector). Vdd refers to the common positive supply of
CMOS circuits (no doubt related to a drain). Vss refers to a common ground
(no doubt related to a source and therefore CMOS as well). Vee is used to
refer to a negative supply (no doubt related to an emitter). Since CMOS is
the most common technology today, if you use Vdd and Vss to describe your
supplies you will most likely have your symbology right (although anyone
would understand you if you got it wrong, so long as you used the right
equivalent). To be the least ambiguous (and to work towards the elimination
of symbols which don't seem to make any sense), it might be best to refer to
signals as +5V or +3.3V and GND.
Howard Henry Schlunder