You should easily be able to run that test yourself. Regardless, the Marking setting can simply be thought as how close defenders will get up tight to their opposition. High marking value means the defenders will be in your face leading to more interceptions, tackles, and requiring you to make quicker decisions with the ball. However, tighter marking also exposes them to be over-aggressive and a quick move or dribble could allow the ball carrier to get around the defender into open field.
On lower Marking values, the defenders will lay off the offensive players and give them a buffer zone. To the point where if you go at them, they could just keep backing away. Even just kind of watch you go right around them.