hi:
in the US, 4 stripes is captain (PIC)
3 stripes is f/o (or pilot qualified flight engineer/second officer)
2 stripes is (was!) a professional flight engineer (at one point you could be an f/e if you were a mechanic and you didn't need to be pilot qualified, but that changed way back when)
1 stripe didn't have anything to do with pilot rankings, though some of our flight attendents had one stripe of a very different color.