What is the speed of cargo ship in comparison to passenger ship?

A cargo ship will run at the most efficient speed that allows it to reach its destination at the desired time, and no faster. Fuel is expensive and the ship doesn't make any extra money for arriving early. Most major shipping lines have complex policies in place that dictate the speed requirements. The speed is monitored many times a day and adjusted as necessary to account for currents, weather, and changes to the arrival time. Ships usually travel between 16 and 22 knots.

Cruise ships will adjust their speed to get from port to port in the time alloted. They typically want to arrive at a port early in the morning, before the passengers get up. They are a little bit less concerned about fuel efficiency and will run slightly higher speeds to make the appropriate arrival times.