"Hackers" often define themselves in 3 categories, these categories are described as follows.
White Hats (Ethical Hackers) are the elitists who use their computing skills in a legal manner rather than for malicious tasks. Commonly, these users are generally known for being the most skilled members in the hacking community.
Back Hats on the other hand are the malicious/criminal side of the hacking community, they generally specialize in items that would be highly illegal. Destructive exploits, viruses, etc are commonly created and set forth by the Black Hats, often for no reasons other than to promote a "zombie" network of computers to be used for future malicious acts.
Grey Hats however are the common medium of the two, they see that there is light in the dark and generally wouldn't intentionally harm a users system or steal information unless it was entirely necessary. They likely wouldn't have a second thought in doing it, and they often just walk a fine line.