(a) Geometrical Isomerism, (b) Optical Isomerism is two types of Stereo Isomerism.
Isomers which differ with respect to the arrangement of atoms of group in space are said to be Stereo Isomers and the Phenomenon is known as Stereo Isomerism.
Stereo Isomerism…
There are 2 types of Isomers. (1) Structural Isomerism, (2) Stereo Isomerism