Which type of structure does a geometric isomer have compared to its counterpart?

Geometric isomers, also known as cis-trans isomers or E/Z isomers, are a type of stereoisomer that have the same structural formula but differ in the spatial arrangement of atoms in their molecules. This difference arises due to restricted rotation around double bonds or within cyclic structures, allowing for distinct arrangements of substituents at specific positions.

In the context of geometric isomerism, the key feature is the arrangement of groups around a double bond or ring structure, where the same atoms are connected but positioned differently in three-dimensional space. This can significantly affect the physical and chemical properties of the isomers, such as boiling points, solubility, and reactivity.

The other options do not accurately describe geometric isomers: having different molecular formulas indicates different compounds entirely, different functional groups would mean they are not isomers, and identical connectivity without spatial variation would not qualify as geometric isomerism since it describes structural isomers instead. Thus, the response highlighting the same structural formula with different spatial arrangements captures the essence of what geometric isomerism entails.