White hat hackers use their skills to help protect against attacks. White hat hackers work to proactively find security weaknesses in order to fix them before they can be exploited by attacks and are compensated for their work.

Whereas a Green Hat hacker is otherwise a noob working to exploit the loop holes in protocols to learn and gain experience

A Grey Hat hacker is in between Black hat and White hat, works for fun, doesn’t necessarily want to help or cause harm.