What is the difference between empirical and molecular formula?

The molecular formula of an atom shows you the actual number of atoms of the elements in a compound. For example ethane has molecular formula C2H6 meaning there are 2 carbon atoms and 6 hydrogen atoms in one ethane molecule. The empirical formula shows the simplest whole number ratio of atoms in a molecule. So for ethane above it would be CH3 ,as a 2:6 ratio can be simplified to a 1:3 ratio by dividing both numbers by 2. Different molecular formula can result in the same empirical formula. For example, the Alkenes C2H4 and C3H6 have different molecular formula but have the same empirical formula.