Hi

BCM and BOARD are two numbering systems for the pins on the Raspberry Pi.

BCM lists pins by their Broadcom SOC channel (GPIO 23, GPIO 24), while BOARD numbers them consecutively (1, 2, 3) starting with the far left pin of the second row of pins.

Pin configuration is supported only by the RPi.GPIO library. GPIO Zero uses BOARD by default.

In RPi.GPIO, the pin numbering system declaration is done with:

GPIO.setmode(GPIO.XX)

Where XX should be replaced by BCM or BOARD.