Unlike Pareto Improvement, a Kaldor-Hicks Improvement can create winners and some losers. Once the whole efficiency (or outcome) improve, we call it as Kaldor-Hicks Improvement (no need to let at least one get better)
We will consider the law A is a better law than B since moving from B to A is a Kaldor-Hicks Improvement. (See the content in ECON4008 Law and Economics)
Since the Pareto Improvement is good for everyone as an individual, the Kaldor-Hicks Improvement is good for the society as a whole. That is, if a law/rule is a Pareto Improvement, it must be a Kaldor-Hicks Improvement.