What is the difference between renin and rennin? ?

Renin is an enzyme while  Rennin is a hormone

Renin's essential capacity is, along these lines, to in the long run reason an expansion in circulatory strain, prompting reclamation of perfusion weight in the kidneys. Renin is emitted from juxtaglomerular kidney cells, which sense changes in renal perfusion weight, by means of stretch receptors in the vascular dividers. Chymosin, referred to likewise as rennin, is a proteolytic compound identified with pepsin that combined by boss cells in the stomach of a few creatures. Its job in assimilation is to turn sour or coagulate drain in the stomach, a procedure of significant significance in the specific youthful creature.

well, i believe that the answer is 2. : 3