1, the appearance of the use: single-fiber optical module only a fiber interface to connect a fiber patch cord, dual-fiber optical module has two fiber interfaces to connect two fiber patch cords. 2, the conventional wavelength: single-fiber optical module contains two different wavelengths, dual-fiber optical module has only one wavelength. 3, the rate: single-fiber optical module in the 100 megabits, gigabits, 10,000 megabits of the rate of the application of the broader range of dual-fiber optical modules are often applied to the 40G and 100G High-speed transmission program.