The difference in animals that are regulators and those which are conformers is that an animal that is regulators use an internal mechanism which is to control internal change in the face of its external fluctuation. In short we can say they are independent. While conformer animals, they match their internal conditions to change according to with the external changes Some animals may regulate internal conditions while others conform the environment.
A good nonliving example of temperature regulation is to control its own temperature. Ectotherms are conformers while endotherms are regulators.
The setpoint is the particular value of maintaining at it or near this allows the animal to achieve homeostasis.