Hello Student
The structural & Functional unit of Kidney is ‘Nephron’
On the basis of position of nephron in to kidneys, they are of two types
1
.Juxtamedullary nephrons – Their glomeruli is present in inner margin of cortex. Loop of Henle is present in medulla. Vasa recta is also present along with them
2.
Cortical nephron – They are present in the renal cortex. Their loop of henle is comparitively short and its not deep into the medulla. Vasa recta is aslo absent. You can see their picture in this attachment

If you want more information over Kidney & its function, you can take it from the following link
https://www.askiitians.com/biology/excretory-products-and-their-elimination/urine-formation-and-kidney-functions.html