What is the difference between epinephrine and norepinephrine?

Both: Are made in the adrenal glands of the body and are released in response to a need for increased energy. The fight or flight phenomenon. The biggest difference is that nor-epi causes more vasoconstriction of blood vessels where epi causes more increase in heart rate and cardiac output through contractility.

Catecholamines: Both agents (and dopamine) regulate the cardiovascular system & blood pressure. Due to their different pharmacologies, they attach to beta (epi) and Alpha (norepi) "receptors" with varying degrees of affinity to produce their effects.

Synthesis & Locale: Norepinephrine (ne) and Epinephrine (e) are both sympathomimetic catecholamines that are synthesized in the adrenal medulla and terminals of sympathetic neurons. Along the metabolic pathway, ne is synthesized first -- and when an enzyme adds a methyl group, you have epinephrine. Ne is the main catecholamine in peripheral tissue and sympathetic neurons. E is mostly made in the adrenal medulla.