PC board vs circuit board

PC board and circuit board both are nouns.

Word	Noun	Adjective	Verb	Adverb
PC board	Yes	No	No	No
circuit board	Yes	No	No	No

As nouns, circuit board is a hypernym of PC board; that is, circuit board is a word with a broader meaning than PC board:

PC board: a removable circuit board for a personal computer; fits into a slot in the mother board
circuit board: a printed circuit that can be inserted into expansion slots in a computer to increase the computer's capabilities

Other hypernyms of PC board include add-in, board, card, circuit card, plug-in.

PC board (noun)	circuit board (noun)
a removable circuit board for a personal computer; fits into a slot in the mother board	a printed circuit that can be inserted into expansion slots in a computer to increase the computer's capabilities