For 10 points, name these compounds that have the same chemical formula but different properties.
One version of these entities consists of pairs denoted dextro- and levo-; molecules that demonstrate that type of this phenomenon are called chiral. Besides the optical ones, or enantiomers, another one of these pairs has cis- and trans- varieties; that is the geometric type of these. The structural type of this phenomenon occurs when two compounds have the same atoms, but those atoms are connected differently to one another. For 10 points, name these compounds that have the same chemical formula but different properties. 
One version of these entities consists of pairs denoted dextro- and levo-; molecules that demonstrate that type of this phenomenon are called chiral.
isomers [accept isomerism; accept stereoisomers before "structural"; prompt on "enantiomers" before mentioned]