The difference between norepinephrine and epinephrine hydrochloride lies in the mechanism of action and the effects produced. 1. The two have different mechanisms of action: Norepinephrine mainly acts on α-receptors, which are mainly found in places such as the mucous membrane of blood vessels and have a weaker effect on the distribution of β1-receptors in the heart. Epinephrine hydrochloride, on the other hand, can activate both α-receptors and β-receptors. Therefore, it has a better effect on both the heart and the vascular mucosa. 2. The two produce different effects: (1) Norepinephrine can mainly activate α-receptors, thus causing smooth muscle contraction of skin and mucous membrane blood vessels, as well as renal vasoconstriction, leading to an increase in blood pressure. (2) Norepinephrine not only stimulates α-receptors to cause vasoconstriction, but also stimulates β2 to act on the myocardium, sinus node, and the conduction system, resulting in enhanced myocardial contraction, increased heart rate, accelerated conduction, and increased cardiac output. Both norepinephrine and epinephrine hydrochloride need to be used under strict medical supervision and should not be abused.