You are confined in a room and given two metal rods. Out of these two rods, one is magnet and the other is the iron rod. They look starkly similar. You dont have any other metal object in the room.
How will you decide which one of those is magnet?
This is pretty simple as the magnet has its magnetic field at poles in general. Then you can just keep one rod on the surface and bring the tip of the other rod towards the center. If the rod which is lying down gets attracted towards your rod, then the one you are holding is the magnet and if it does not then the one lying down is the magnet.