I remember I use to have the same question myself. I can try answering it using my endocrinology book.
Epi acts primarily as a hormone while norepi serves mainly as a nuerotransmitter (but sometimes it does serve as a hormone).
Most of us have heard of the fight-or-flight response where stress causes us to release adrenaline(epinephrine). It also causes us to release norepinephrine. In humans, norepi and epi are released at a ratio of 1:4
Epi and norepi have similar physiological effects, but differ in several important respects. For instance, epi elevates heart rate and affects metabloilsm more than noreipi. In contrast, norepi is a more potent vasoconstricter than epi.
Hope it kinda helped
