Both are apolipoproteins with the function of transporting lipids, the difference is that they exist on the surface of different lipoproteins. 1. ApoA: mainly exists on the surface of HDL, mainly synthesized by liver, if liver function is impaired, it will lead to the decline of ApoA, because it is the apolipoprotein of HDL, so it can reduce the occurrence of atherosclerosis, so as to reduce the occurrence of cardiovascular and cerebrovascular diseases. 2. ApoB: mainly present on the surface of LDL, also synthesized by the liver. However, ApoB is implicated in hyperlipidemia, i.e., elevated ApoB tends to increase the risk of atherosclerosis, leading to coronary heart disease and other cardiovascular diseases. If abnormalities of ApoB are detected during a physical examination, it is recommended to consult a physician for professional guidance.