In a controlled experiment what term is used to describe the many factors that might be different between the experimental and control groups

The factor that is different between the control and experimental   is known as the independent variable. This variable is independent because it does not depend on what happens in the experiment.

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.