How do the density of wood cube and metal cube compare?

This is not a sensible question. There are many types of wood, and many types of metal. It depends which ones you pick. Balsa wood has a very low density, lignum vitae is much higher. Most woods are less dense than water (so they float) but a few are denser. Most metals are more dense than water, but a few, such as sodium and potassium are less dense. Overall, I suppose most metals are denser than most woods, but potassium is less dense than some forms of eucalyptus wood.