isomer

each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties.

enantiomer

mirror image molecules, same molecular formula

structural isomer

one of two or more compounds that contain the same number and kinds of atoms but that differ significantly in their geometric arrangement

cis-trans isomer

geometric isomers, where the functional group is placed differently with regards to the double bond.

cis isomer has molecules on one side of the double bond. A trans isomer has molecules on the other side of the double bond