UPS means uninterruptable power supply, and SPS means Standard Power Supply. A UPS is used to protect hardware such as data centers, telecommunication equipment, electrical equipment, and computers.
UPS is a device that supplies electric power for a short period of time when the power source fails. The SPS, just like the UPS, has a battery that provides power to the computer only when the AC loses its power.
SPS have to detect power out before switching over to battery to supply power while switching over the SPS all power may still be lost while the UPS is always on stand by.
UPS is more effective than SPS. The SPS higher quality system has a ferroresonant transformer that offers small power for switching to take place.