Final answer:
Osmosis is the movement of water from a less concentrated solution to a more concentrated solution through a semipermeable membrane. Reverse osmosis is the opposite, where water flows from a less concentrated solution to the more concentrated solution under applied pressure. Reverse osmosis is often used for water purification.
Step-by-step explanation:
Osmosis is the process of water moving from a less concentrated solution to a more concentrated solution through a semipermeable membrane. Reverse osmosis, on the other hand, is the net flow of water from the less concentrated or pure water across the semipermeable membrane to the more concentrated solution, driven by the application of external pressure higher than the osmotic pressure. Reverse osmosis is commonly used for water purification, including desalination of seawater and softening hard water.