Nootropics feed the body nutrients it needs that we aren't likely getting in our foods. The better your nutrient intake the better you work. Nootropics go into an area where many people find themselves deficient in and repair the damage while fueling the body with nutrients that can make that happen.
Smart drugs don't generally come from the basic vitamin section of the store, they are more powerful and work directly on specific things. They are artificially created in a lab with natural nutrients in foods but in such a way that the body can use them more readily for cognition and other things. One of the most powerful Nootropics on the market today is Noopept and this is a derivative of Piracetam which is a derivative of Gaba (found in many foods and naturally occurring in your brain).