The Difference between protesting and riots is simple.
Protesting: Protesting is a usually a peaceful argument for change, in which people seek change in something they find to be wrong and want to change. Usually peaceful protests may turn into riots if people feel rejected and think that nobody cares about there what they want to change they may take action to gain people's attention.
Rioting: Is when people are so angry that they may take to the streets to destroy, vandalize and ect. In the name of what they are arguing about. For instance people rioting over Black Lives Matter may be smashing windows and raiding stores while burning and taking over cities.
Explanation: I hope that i have answered your question. :)
