Everyone wants to be intelligent, which is not the case for 'intellectual'. The term is partly pejorative. Why is that?
Intelligence is the ability to synthesize different information. These may be contradictory, or seem foreign to each other. Intelligence is to overcome these difficulties in a synthetic concept that hides them without actually making them disappear.
The intellectual is a mind occupied by synthetic concepts, which sometimes makes him lose sight of the conflicts that are at the origin of them. The solution has erased previous conflicts and inconsistencies. Yet is it entirely satisfactory? Are there no other possibilities?
For people who still experience intellectually resolved conflicts, the academic solution may seem mediocre, or be a tasteless mental fast-food. The academician learned his solution, he did not live or experience the conflict of origin. It may be blind to other effective methods of solving it.
I thus contrast the academician with the inventor. Both are very intelligent; the former tends to digest, classify and synthesize existing knowledge, while the latter tends to produce new knowledge from the initial data.
Both are intellectuals but use their intelligence very differently. The academician closes the representations around a subject, with an epistemic look. While the inventor opens the range of potential representations by adding his own, with an ontological look.
These two mental activities are complementary and indispensable. The smartest minds are those capable of alternating between the two eyes, to add new synthesis over the existing ones.