"cause" is a noun and a verb. To cause trouble. Johnny was the cause of the trouble. "Because" is a connector word, followed by a verb or a verb phrase: "I did it because she told me to." Sometimes "because" is abbreviated to "'cause" in informal or careless speech: "I did it 'cause she told me to."

The difference is in the significant of these words. Because is usually used to explain something "I didn't visit you because I was busy yesterday" Cause is used to express a reason of something: " cause I was learned it before, I wouldn't agree to take this course again" By the way, there is "Because of" to explain that happens are result of something that had happen before:" I couldn't shoot him because of my scope had been(was) contorted"