A 28-year-old man is brought to the emergency department after a fall from a motorcycle. On examination, he has multiple injuries on his right arm and leg. On the arm, there are areas of superficial skin loss with oozing of blood and tissue fluid, but the wound edges are irregular and tissue planes are not clearly separated. On the leg, there is a deep wound with clean separation of tissue planes and bleeding from cut vessels. Which single feature best distinguishes the laceration on the leg from the abrasion on the arm?