What is the difference between stereoisomerism and optical isomerism?

Isomers are compounds with the same molecular formula but different arrangement of atoms in space (or structural formula). Stereoisomers (E/Z isomers) have different arangements of bonds in space. This occurs in alkenes,where the carbon atoms forming the double bond are attached to two different groups. - Here I would draw the 2 different type of stereoisomer, E and Z to show their difference Optical isomers are those in which there are 4 different groups attached to a carbon atom, resulting in the formation of 2 isomers that are mirror images of one another, but not identical. - again would draw