Coffee and coaine are not actually worlds apart in terms of mechanism of action, they both act on the same brain pathway though coffee has a limited ability to activate this pathway in comparison to cocaine.
This is a completely meaningless comparison. Even things that behave waaay more similar than cocaine and coffee in terms of brain chemistry can have even more disparate effects. And I was talking about the effects.
This meaningless comparison is a fundamental concept in psychopharmacology. Different substances can have different effects whilst acting on the same pathway. And to your point re: "effects"it should be noted the SAME substance can have very different effects (biphasic effects) depending on dose (alcohol being the key exmaple).