Final answer:
Identical molecules have the same molecular structure. Isomers are molecules that share the same chemical formula but have different arrangements of atoms and/or chemical bonds.
Step-by-step explanation:
Identical molecules have the same molecular structure. Molecules that share the same chemical formula but differ in the placement of their atoms and/or chemical bonds are called isomers. Isomers have the same number and type of atoms arranged differently in space.