Dynamic load rating is the amount of weight an actuator can pull or push safely when being powered. Static load rating is the amount of weight the actuator can hold or withstand without back driving when it is not being powered. For example, let's just say you have an actuator installed on a window and the static load rating of the actuator is 100lbs, it could experience backdriving when there is a high wind event, which means there will be more pressure exerted on the actuator which would exceed the 100lbs load rating of the actuator.