Caffeine in a form you can consume through drinking or eating is an alkaloid salt. That means it is a polar solute and can be dissolved in water and digested. To be able to smoke it you need to cleave the acid off and return it to it’s base form. In it’s base form it is no longer water soluble since it is now non-polar. The base can be vaporized (usually through smoking). The term “Free Base” is from the process of returning alkaloid salts to the base form for consumption. The best way to do it is via an alkaloid acid-base extraction if you don’t mind working with non-polar solvents like naptha or chloroform but simple baking soda will do the trick in a pinch.

I have never tried caffeine free base (or any free base alkaloid) but as @LTB said, it should be more potent or at least enter your system faster.