A young man waring black and carrying a skateboard looks at an outdoor skateboard park.
A guy with a skateboard is looking at a park to skateboard.
A man is a type of guy; he is carrying a skateboard, so a skateboard is with him; a skateboard park is a park in which to skate, and the thing he's carrying indicates that's what he wants to skate with.
A young man and a guy are equivalent, carrying a skateboard means with a skateboard, looks at a park to skateboard (outdoor skateboard park).
A man carrying a skateboard implies that it is a guy with a skateboard.