There is no difference, it depends on how close you are to the person you're talking to.
"Anda" usually used to a person that looks or sounds like around the same age as yours or to your audience. Usually used in articles and sometimes in talks (other people as your audience).
"Kamu" and "awak" used in conversation to friends for respects, "engkau" or usually shorten as "kau" or "ko" is the most common phrase used among Malaysian towards their close friends (same age). Also widely used in poetry.
