The term used for molecules that have identical molecular formulas but different arrangements of atoms is isomers.

There are different types of isomers, including:

* Structural isomers have different connectivity of atoms.

* Stereoisomers have the same connectivity but different spatial arrangements of atoms. This includes:

* Enantiomers which are non-superimposable mirror images of each other.

* Diastereomers which are stereoisomers that are not enantiomers.

Let me know if you want to learn more about any specific type of isomer!