They are all imperial thread standards. BSF (fine thread) and BSW (whitworth, coarse thread) is a British standard. UNF (fine thread) and UNC (coarse thread) is an American standard.
The BSF/BSW have a thread angle of 55°, The UNF/UNC have a thread angle of 60°. Can you mix they up and use? UNF (American fine) and BSF (British fine) they have a different thread pitch. So they won’t work together.
The UNC (American coarse) and BSW (British coarse) they will work, but the connection, due to a different angle of the thread won’t be as strong as it should be.
