Open-cell spray foam insulation has tiny cells which are not completely closed. Open-cell is usually less expensive because it is developed using fewer chemicals. Open-cell is superior as an air barrier and is sponge-like in appearance. It is often used to insulate interior walls because it minimizes outdoor noise intrusion.
Closed-cell spray foam insulation is a higher-density foam than open-cell. The structure of the actual cells is more compact. It is both an air barrier, water-resistive, and vapor barrier. Closed-cell can be installed anywhere in the home