What is the difference between aluminum and aluminum?

There is no difference in the meaning. The spelling aluminium is the international chemical term recommended by IUPAC (International Union of Pure and Applied Chemistry), in line with other names of elements (such as sodium, chromium, cadmium). In the US it is specifically spelled as aluminum. The pronunciation also varies. When it is spelled 'aluminium' it usually ends with the sounds 'nee-um'. When it is spelled 'aluminum' it is ends with the sound 'num'.