Final answer:
Smooth muscle tissue, a part of the tunica media, is found in arterial walls but not in capillary or venule walls.
Step-by-step explanation:
The type of tissue found in the walls of the arteries but not in the walls of capillaries and venules is smooth muscle tissue. This tissue is part of the tunica media, the middle layer of the artery wall, which is much thicker in arteries compared to veins to handle higher pressure. Capillaries, being the smallest blood vessels, have walls that consist of little more than a single layer of epithelial cells and do not contain smooth muscle or other complex structures found in the artery walls.