Seeing as how they're the same drug (cocaine) and all, I think that it would be different for everyone, like because of unique body chemistry and depending on how the person is using each drug, it'd be more a patient by patient, case by case basis. Consider how different people's tolerances are, not even like two different people, but one person in different environments than their usual "getting-high-place" or otherwise stepping outside of their comfort zone can have radical effects on the outcome of the drugs effects.
The cocaine HCl may inhale larger lines to compensate for desired effect, or injected for that notorious soul-destroying bell-ringer.
Then there are the smokers of the freebase 'caine, who tend to compensate by packing bigger rocks, or purifying their product, or inhaling the vapor deeper into the lungs, holding the hit, etc. There are even people who prefer to inject CRACK cocaine in an acidic solution (...ouch!) because the quality of cocaine HCl in their area is so bad..... So every one is different; we can't make sweeping generalizations here.
You asked which drug is "harder on the heart", which is a pretty vague question and is like comparing cocaine with cocaine.