Understanding is the ability to lift the meaning out of the facts, and Wisdom is knowing what to do next. Those with knowledge are able to collect, remember, and access information. They are scholars. Those with understanding are able to abstract the meaning out of information. They are teachers.
Understanding is a lens which brings the facts into crisp focus.
Those with wisdom know which principle to apply now. We see the truth of both. They do the right thing. In contrast, there are many who have great knowledge and understanding, but consistently do the wrong thing. Wisdom, in this sense, is the goal, and knowledge and understanding only have eternal value as they result in wisdom, or what we end up doing.