Difference between servo_output_raw and PWM signal on Pixhawk servo rail

I been searching for answers to this the whole day but haven’t made much progress. I’m trying to determine the difference between the values retrieved from the pixhawk using the mavlink_msg_servo_output_raw message header and the actual value sent to the servo rail pin (specifically for the throttle channel). So far I’ve determined that the armed status of the controller doesn’t affect whether the channel is active or not.

Any help would be greatly appreciated.