Final answer:
Endocytosis is the process by which a cell takes in particles or substances, while exocytosis is the process by which cells release particles or substances from their cytoplasm to the external environment.
Step-by-step explanation:
Endocytosis is a process in which a cell takes in particles or substances from the external environment by engulfing them with its cell membrane. Phagocytosis is a type of endocytosis that involves the ingestion of large particles, like invading pathogens, by immune cells. On the other hand, pinocytosis is a type of endocytosis that allows cells to take in fluid containing dissolved substances. Receptor-mediated endocytosis is a selective type of endocytosis that occurs when specific ligands bind to receptors on the cell membrane, triggering the intake of the ligands.
Exocytosis, on the other hand, is the process by which cells release particles or substances from their cytoplasm to the external environment. It is the opposite of endocytosis and is essential for various cellular functions like the secretion of proteins and neurotransmitters.