Risk can be defined as a chance you take, knowing it could come at a cost, and it might also mean that there is a chance for injury or personal loss. Uncertainty, on the other hand, is when you are in a state of doubt or confusion.
For example, someone at work could bring up the idea that they want to pursue, and you may be uncertain that it will work, but there is no personal loss if it doesn’t. An example of risk could mean that when someone drinks and drives, they are taking a risk by getting behind the wheel, and they are placing themselves and other drivers in harm’s way.
If a person is uncertain about something, it could be that your uncertainty is unwarranted because it is coming from the doubt in your mind and not reality. When there is a risk, there is usually more at stake.