What is a primary difference between arteries and veins?

The primary difference highlighted in this context emphasizes the anatomical positioning and structural characteristics of veins compared to arteries. Veins are often located more superficially in the body compared to arteries, which tend to be deeper. This positioning allows veins to be more accessible for practices such as venipuncture. Additionally, when not filled with blood, veins can collapse due to their thinner walls and less muscular structure, which contrasts with the more rigid and muscular walls of arteries that maintain their shape under pressure.

The mention of superficial versus deep placement is significant as it ties into practical applications in clinical settings, such as IV therapy, where understanding the anatomy of the vascular system can aid in effective treatment delivery.

While arteries do transport oxygenated blood (with the exception of pulmonary arteries) and have a more robust three-layer structure than veins, these points are secondary to the emphasized anatomical differences in the question.