Corrected me
The term cracking is more about modifying some executeable program and skip its limitation, such as activated some functions that being disable due to trial, or make the program skip the need to enter registration code, also making other executeable to alter program, and much more. And in extend meaning it modified limitation not just to exe program, but until in the real live, but the intention is good. Some crackers, write trainer program for games but they said it for fun, they bought the game and suggest other to buy it. No bad intention there.
Hack more refer to network or data communication area. Meaning that it about breaking the rules that limited access to people. In networking, there is always limit to enter something, recognized user, the administrator, guest, all have different authority and resource that they can have. Hack is about to ignore this rules, by gaining access that not supposed to be. The good one do this hacking for good purpose, warning the administrator that his/her system has somekind of hole or weakness that could do harm, other for testing some security and guard system from bad. Not always make sense why people do this, may be for fun, may be for fame, who knows.
The bad one do this to harm other people, make other system down, spying other, destroy other data, change his own bank account, and other unimagineable bad effect in the area of computer usefull in.
In the end the difference of cracking and hacking is quite blur, they could be mix together and what we named that?
And what kind of people could be named pro in this area? Not too clear, the pro in hacking is the one who never known, then he never exist, if he never exist then there is no pro. But some says if in the community, known respected people give credit to someone than the one can named pro already, but never there is a sharp line about that, quite hard too to differ the good and bad one in this matter. But if the effect not harming and there usefull to many people, quite good enough I guess.
Hacking and cracking is about gaining power, there's no wrong in that. But power come to people and its all end to the people, like you could use knife to cut meat, that very usefull, you could also murder someone with that. There’s no wrong with the knife, the people I guess is the problem.
I hope I help some explanation not more confusing.
Corect me if I’m wrong.