It is very interesting that the word "mind" appears in the question, and the tags are "intelligence" and "mind".
Actually, all these words are almost synonymous (especially in everyday speech), but I personally share them.
Intelligence in my understanding is just erudition, the ability to operate with data arrays in your head. This is great, but it seems to me that this is not at all the main thing.
Reason is a kind of "common sense". That is, a mixture of different things in their daily application, for example, how best to take out a loan, where to relax at this time of the year with some set of initial parameters, etc. This is a very good thing, and already much closer to the "mind" - because here we operate with completely different areas and literally join them "on the fly", but still not quite that.
Um - I call it "mental alertness", that is, the ability to obtain maximum conclusions with a minimum set of data. That is, the whole dialectic is practically impossible without this mind - with the help of the intellect we can understand the results of others and evaluate them, but only with the help of the mind can we realize and come to this on our own. Actually, I think that this is the most important thing - it is always interesting to talk to such a person, even if he does not know anything at all (he will find very interesting connections and draw parallels where you would not even think about it).
It seems to me that smart people realize that their beliefs and views are not always the only correct one. And a smart person will never become boring and aggressive to impose his great speculations on another. A smart one always strives for all-round development, and if something is unfamiliar to him, he will not immediately say "oh well, what nonsense" (be it avant-garde art, a provocative article in a newspaper or a new scientific theory), but first thoroughly study the background, etc. .д.