Technical difference
Core Diameter—Single mode fiber has a small diametral core(8.3 to 10 microns) that allows only one mode of light to propagate. Multimode fiber optic cable has a large diametral core(50 to 100 microns) that allows multiple modes of light to propagate.
Light Source—Multimode devices usually use a LED or laser as a light source. While single mode devices use a laser, or laser diode, to produce light injected into the cable.
Practical Difference
Distance—Light travels a longer distance inside single mode cable than it does inside multimode. So multimode fiber is suitable for short haul application, allowing transmission distances of up to about 550m at 10Git/s. When distance is beyond 550m, single mode fiber is preferred.
Price—Multimode fiber usually cost less than single mode fiber.
Bandwidth—The bandwidth of single-mode is higher than multimode as much as 100,000 GHz.