How do you distinguish between arterioles and venules?

Arterioles are small blood vessels that carry oxygenated blood away from the heart to the capillaries, while venules are small blood vessels that collect deoxygenated blood from the capillaries and carry it back to the heart. Arterioles typically have thicker walls and are more muscular than venules to help regulate blood flow and pressure, while venules have thinner walls and lower pressure.