The difference between an ethical hacker and a hacker is something that can easily get you into an argument. Just saying the word hacker in the wrong place can get you into an hours-long conversation of the history of hacking and how hackers are all good guys who mean nothing but the best for the world. Others will tell you that hackers are all evil and have nothing but bad intentions. In one case I was even told that hackers were originally model-train enthusiasts who happened to like computers.
You must understand that for us, hackers are separated by intentions. In our worldview hackers who intend to cause harm or who do not have permission for their activities are considered black hats, whereas those who do have permission and whose activities are benign are white hats. Calling one side good and the other bad may be controversial.
Black Hats They do not have permission or authorization for their activities; typically their actions fall outside the law.
White Hats They have permission to perform their tasks. White hats never share information about a client with anyone other than that client.
Gray Hats These hackers cross into both offensive and defensive actions at different times.
Suicide Hackers This relatively new class of hacker performs their actions without regard to being stealthy or otherwise covering up their assaults. These individuals are more concerned with carrying out their attack successfully than the prison time that may ensue if they are caught.
Another type of hacker is the hacktivist. Hacktivism is any action that an attacker uses to push or promote a political agenda. Targets of hacktivists have included government agencies and large corporations.