Does This Sound Like Conduct Disorder Or Behavior Problems? My

Does this sound like conduct disorder or behavior problems?
My brothers younger son is 7 years old and he has extreme temper tantrums that last for hours and our mother has had to come get him on numerous occasions. I have seen this child call his father stupid, and i have seen him snatch a phone out of his mothers hand when she firmly told him to wait until she got off the phone to attend to him.

My brother and his wife have been to his childs school LOTS of times because of his behavior and his son even assaulted the principal on one occasion. He throw a rock through someones window for fun then lied about it. We also found out he was carrying a pocket knife to school.