PC board and Plug-in

PC board noun - A removable circuit board for a personal computer; fits into a slot in the mother board.

Plug-in and PC board are semantically related. In some cases you can use "Plug-in" instead a noun phrase "PC board".

Plug-in noun - A printed circuit that can be inserted into expansion slots in a computer to increase the computer's capabilities.

PC board and plug-in are semantically related. Sometimes you can replace phrase "PC board" with "Plug-in", this phrases are similar.