What is the difference between Risk & uncertainty?

risk is known whereas uncertainty may result in a risk or may not.

Uncertainty is a lack of complete certainty. In uncertainty, the outcome of any event is completely unknown, and it cannot be measured or guessed. Here you don’t have any background information on the event. Risk is an uncertain event or condition that, if it occurs, has a positive or negative effect on one or more project objective such as scope, schedule, cost, and quality

Uncertainty and risk are closely related concepts in economics and the stock market. The definitions of risk and uncertainty were established by Frank H. Knight in his 1921 book, "Risk, Uncertainty, and Profit," where he defines risk as a measurable probability involving future events, and he argues that risk will not generate profit. Risk is calculated using theoretical models, or by calculating the observed frequency of events to deduce probabilities.

Uncertainty is not quantifiable because future events are too unpredictable, and information is insufficient. The uncertainty of the event is not something that can be calculated using past models. Though randomness of events underlies both principles, it is important to distinguish the differences as they relate to investments. An investor has the opportunity to calculate the risks by deducing past probabilities to protect his or her investment portfolio. Uncertainty is not quantifiable and therefore does not offer the same opportunity to protect an investment. Both principles work in tandem and do apply when in investing situations, or even prospects of investing on the stock market.

Uncertainty is a risk scale. Risk will be higher in case of uncertainty is more. And risk will be less when uncertainty changes to certainty.