You said similar. There must be something different about it that causes a noticeable difference between near-amphetamine stimulation and happiness to the feeler. Coke is much more than just feeling happy, excited, or that tingly feeling that you get when you did something out of love (which is probably nothing more than adrenaline). Cocaine gives you a lot of adrenaline, yes, however it increases concentration, makes you jumpy, speeds your heart rate, and once hooked you'll easily be made paranoid.
It also depends on the severity of the action doesn't it? One time I floored my truck across a highway in 2nd gear and almost got hit by a car going 55-60. My adrenaline was so pumped that I had to park somewhere until I stopped laughing, shaking, and itching. Another time I was walking into a mall, seeing people putting dimes or quarters in a bucket for donations and I walked up and put two dollar bills in the bucket. I smiled for a minute or two. When comparing the action done out of destructive attitude and annoyance, with the action done out of empathy, the former definitely granted me more adrenaline.
Perhaps it is the same receptors that are fired into the brain for adrenaline, but the amount of receptors will vary on the intensity of the action or drug. That's just my guess. I wouldn't doubt this was said, so no need for sources, I'm just saying it's definitely either not well detailed or the person who did the actual study was very, very lazy and in all probability, if they're that lazy, they might even need cocaine (just kidding).