What is the difference between limit and priority?

Limits allow you to precisely control network bandwidth of single connection or of whole application, but in some cases it could be too restrictive. Priorities are more gentle way how to control the bandwidth. If one application has higher priority than other, NetLimiter will prioritize its traffic over the other's traffic. This will allow it to run at its full potential (speed), but it will not restrict the application with lower priority as much as limit would.