Zero PCB is used for experimentation (cannot be mass-produced or sold to the users) and whose bonding wires are available except there is no specific circuit connection;

General purpose PCB means a finished circuit board with a certain electrical connection and which can be mass-produced.

BTW, zero PCB is still used by hobbyists, while general purpose PCB is for industrial use. And industrial pcb are used everywhere and can be found inside any gadget. Meanwhile, general purpose PCB are far costly than zero PCB but they are quite easy to fabricate.