[blackguardx]

It is mainly an architecture difference. An FPGA is typically made up of many logic blocks that contain a programmable look up table (LUT) connected to a flip flop. There are also various multiplexers (muxes) that route signals around the flip-flop or to other neighboring logic blocks. In this way, you can chain many of these logic blocks together to create your desired circuit.

A CPLD typically has a network of And or Or gates leading to the pins of the device. The outputs of these gates then feed into the complementary gate (Or for And and And for Or) and then most likely into flip flops. You program the device by selectively connecting the pins through a switching matrix to the various elements of the first logic array and then another switching matrix to the various elements of the second logic array. There is also the possibility for a third switching matrix for feedback through the system.