What is the difference between endocytosis and exocytosis?

Endocytosis and exocytosis are active transport mechanisms that cells use to transport macromolecules that are too large to pass through the cell membrane passively.

Features of Endocytosis

• Process by which cells actively transport substances into a cell by engulfing them in a vesicle.
• Decreases the size of the cell membrane.
• Helps to absorb nutrients for efficient cellular functioning and eliminate pathogens and old or damaged cells.
• Occurs over three pathways – phagocytosis, pinocytosis, and receptor-mediated endocytosis.
• Vesicle is formed from cell membrane. It then gets into the cytoplasm.
• Example of endocytosis - White blood cells being engulfed by phagocytes.

Features of Exocytosis

• Process by which cells actively expel molecules out of the cell into the extracellular fluid. 
• Increases the size of the cell membrane.
• Facilitates communication between cells, repairs cell membrane, and eliminates toxins and waste products.
• Occurs through three pathways – regulated, constitutive, and fusion of vesicles with lysosomes
• Vesicle is formed in the Golgi apparatus. It then fuses with the cell membrane.
• Example of exocytosis - Releasing neurotransmitters to facilitate cellular communication