What are the key differences between the Kaldor-Hicks and Pareto criteria when evaluating the efficiency of economic policies?

The key difference between the Kaldor-Hicks and Pareto criteria is that the Pareto criterion requires that a policy change must make at least one person better off without making anyone worse off, while the Kaldor-Hicks criterion allows for some individuals to be worse off as long as the overall gains exceed the losses.