Wisdom is justified, true happiness.
Knowledge is often described as "justified, true belief". This means, if you hold a belief, and it is true, that is not enough to call it knowledge. It must also be a justified belief. Meaning, there must be a good rational reason for the belief that is somehow causally linked to the external fact. So, a person could hold a belief for foolish reasons, that happens to turn out to be true by chance, but this is not knowledge.
On the other side of the coin, the belief being justified is also not reason enough to call it knowledge if it is not also true. Sometimes we have a good reason to believe something, but the evidence on hand simply points in a direction that isn't true. No matter how justified, if the belief isn't actually true, then it isn't really knowledge.
Now for wisdom...
Wisdom can be described as "justified, true happiness". This means that there are no distraught sages (ultimately wise folks). If a person is wise, you will know their wisdom by its fruit, which is happiness. While all sages are happy, not all happy people are sages. A person could be a 'happy fool'. In other words, they may be happy for ignorant, naive, shallow, or unrelated reasons. This is why I say that the happiness must be justified. A sage is happy because the sage understands the true way to happiness and reasons for happiness. The happiness must also be true happiness. In other words, it must be a deep enduring contentment and joy that transcends external circumstance, and not be a happiness based on shallow transitory pleasures.
So, if someone appears to be typically grouchy, mean-spirited, sad, upset, angry, bitter, or erratic in their happiness - then it is reasonable to question the wisdom of their ways. Beware the path they have chosen, unless you too wish to be similarly unhappy. True Happiness and relief from suffering is, after all, is the ultimate purpose of spiritual practice.