Consequentialism is the view that the moral status of an act is determined solely by the value it brings about. When combined with various other views, consequentialism yields various moral theories.
Combining consequentialism with welfarism—the view that well-being is the only source of value—yields utilitarianism, the theory that the morally right act is the one that maximizes well-being. When utilitarianism is further combined with hedonism as an account of well-being, the result is hedonistic, or classical, utilitarianism—an influential theory held by Jeremy Bentham, John Stuart Mill, and Henry Sidgwick, according to which the morally right act is that which maximizes the surplus of happiness over suffering. If instead utilitarianism is combined with a desire-fulfilment account of well-being, the result is preference utilitarianism, which holds that the morally right act is that which maximizes preference satisfaction.
Consequentialism may instead be combined with a non-welfarist axiology. One such theory is pluralistic consequentialism, on which the right act is that which maximizes the overall degree to which various different values—including both well-being and non well-being sources of value—are realized.
Consequentialist views also differ about whether the right act is the one which maximizes actual or expected consequences. Objective consequentialists hold that the right act is the one which actually maximizes consequences regardless of whether they were foreseeable by the agent. By contrast, subjective consequentialists hold that the right act is the one which maximizes expected consequences, defined as the sum of the value of each possible outcome multiplied by its probability of occurring.
Another important difference between consequentialist views is whether the nature of the beneficiary influences how we weight the good. Classical utilitarians, for example, would argue that one unit of pleasure is equally good no matter who experiences it, while prioritarians argue that it would be better if that unit of pleasure was experienced by someone who is relatively worse off.
Sinnott-Armstrong, Walter. 2015. Consequentialism. In Edward Zalta (ed.), Stanford Encyclopedia of Philosophy.
Wikipedia. 2016. Consequentialism.