Geometrical isomers differ due to:

Geometrical isomers, also known as cis-trans isomers, arise from the restriction of rotation around a pi bond, typically found in alkenes. In these compounds, the presence of a double bond creates a rigid structure that prevents the free rotation of the atoms or groups attached to the carbon atoms involved in the double bond. Thus, two different spatial arrangements can exist due to the different positions of the substituents around the double bond.

In cases where there is a double bond, if two identical or different groups are on the same side of the double bond, it results in a "cis" configuration; if they are on opposite sides, it results in a "trans" configuration. The inability to rotate freely allows these distinct arrangements to coexist as separate isomers, leading to differing physical and chemical properties.

The other options do not adequately explain the formation of geometrical isomers. The rotation around a single bond does not create these distinct configurations since single bonds allow for free rotation. The position of carbon chains can influence structural isomers but does not directly relate to geometrical isomers. Lastly, while different types of functional groups can create structural isomers, they do not pertain to the concept of geometrical isomerism which hinges