Alveoli:

1. Shape: They are rounded or polyhedral.

2. Components: Alveoli are single entities.

3. Blood Capillaries: They are of one type and lie all over the alveoli.

4. Materials: They deal with respiratory gases.

5. Function: Alveoli perform exchange of gases between blood and inhaled air.

6. Processes: Gaseous exchange occurs through diffusion.

Nephrons:

1. Shape: They are elongated tubules.

2. Components: Each nephron has two components-Malpighian capsule and renal tubule. Renal tubule has three parts - PCT, loop of Henle and DCT.

3. Blood Capillaries: Blood capillaries form two patches glomerulus and peritubular capillaries.

4. Materials: They deal with body fluids.

5. Function: Nephrons bring about separation of waste products from blood.

6. Processes: Urine formation occurs through ultrafiltration, reabsorption, secretion and osmosis.