"Port", "starboard" are unambiguously defined relative to the vessel. "Left" and "right" require specifying or guessing a point of reference.
For instance if you're facing port and I ask you to take two steps forward, you could either take two steps to port or two steps towards the bow. If I tell you to take two steps to port then the direction is unambiguous.
For instance if you're facing port and I ask you to take two steps forward, you could either take two steps to port or two steps towards the bow. If I tell you to take two steps to port then the direction is unambiguous.