Regular cocaine powder is cocaine hydrochloride. Crack is made by mixing cocaine hydrochloride with ammonia and then burning off the hydrochloride which makes it a freebase. People don't smoke regular cocaine until it has been turned into freebase. Smoking cocaine powder is just wasteful compared to snorting it.

Smoking crack results in a more rapid absorption into the bloodstream—compared to snorting the powder. Therefore, the effects are more rapid and quicker to dissipate than if someone just snorted cocaine.

Crack is cheaper than powder cocaine, because crack has less cocaine per dose, and is still very potent. So poorer areas get flooded with crack, as no one can afford to be addicted to cocaine powder in the lower class.

So, in conclusion, it is absolutely discriminatory to have harsher punishment for crack than cocaine. Even if crack is more potent, it has less illegal substance in it by weight than cocaine powder does.