This is pretty easy to search, but also intuitive when you consider crack is most often smoked vs cocaine being absorbed through your nasal mucosa. Here are a few highlights from this comprehensive review, which also covers the very real socioeconomic differences in use patterns:

By virtue of its hydrophilicity, cocaine hydrochloride is generally consumed by ‘snorting.’ ‘Crack’ cocaine is generally the only form of cocaine that is smoked—this is due to the fact that cocaine hydrochloride has an elevated boiling point and does not vaporise at the temperatures of combustion.

®outes that involve the respiratory system…allow for the stimulant to reach the brain circulation in around 6 to 8 s; the inhalation route presents higher peak plasma concentrations that are reached faster when compared to intranasal administration. It should be noted that, for the intranasal route, the vasoconstrictive properties of cocaine slow down the drug’s own absorption, causing a 60-min delay of peak plasmatic concentrations. In terms of bioavailability, the inhalation route has the greatest bioavailability, which surpasses 90%, while the intranasal route has roughly 80%.

The abuse and dependence of cocaine is strongly related to the drug’s capacity to induce the release of dopamine within the mesocorticolimbic circuit (also known as the reward system). As the user continues to consume cocaine, desensitization occurs and so larger doses are necessary to induce stimuli of the same magnitude as before, as well as to minimize withdrawal symptoms.

Another difference of inhalation vs intranasal:

Smoking ‘crack’ leads to the formation of another biomarker of exposure, AEME, which is the main product of cocaine’s thermal degradation. In vitro and in vivo studies show that AEME appears to have effects on the cardiovascular system, by acting as a muscarinic agonist. Furthermore, neurotoxic effects were also reported for this metabolite.