Minime KDE is a full KDE implementation, with a minimal installation of any of the "extras." You go in and add what you want/need.
The Zen-Gnome release is the same as Minime, but with the Gnome desktop.
Both Phoenix and PCLXDE are GTK based, and both are lightweight (and VERY fast) desktop environments. Both are capable on running on hardware as modest as a P-II with 128 KB RAM.
Hopefully, this answers your questions.
And ... BTW ... welcome to the PCLinuxOS forum!