What would be different in your observations between Na and K?
Well, melting point for one..........
And potassium is much softer than sodium metal. And sodium has a much higher melting point than potassium.
And chemically (not that you will be allowed to do this test!), potassium metal is a lot more reactive. Treat potassium with
On the other hand, sodium metal will react fairly vigorously with ethanol, whereas potassium will give a few flames, and a violent reaction.