During a routine autopsy study, pathologists examine thrombi from two distinct sites. One is an occlusive thrombus in the left anterior descending coronary artery of a 72-year-old man with a history of hypertension and atherosclerotic plaque rupture. The other is a thrombus in the femoral vein of a 65-year-old man who underwent hip replacement surgery and remained immobilized for several days postoperatively. Histological analysis reveals structural and compositional differences between these thrombi. Which of the following statements best characterizes the differences between the arterial and venous thrombi described above?