Fairness is important in all human social relations, wether large or small. But there are two different kinds of fairness. Experts call this equity and equality. Equality means treating everyone the same (obviously). Equity means giving out rewards in proportion to what each person contributed. Under equity, the person who contributes more or better work gets a proportionately bigger share of the reward.
Roy Baumeister, Is There Anything Good About Man?, 2010