APC's flagship line has been the Smart-UPS (which even has a wikipedia entry). In the past, most SmartUPS units output a true sine wave. APC's cheaper BackUPS line was the UPS with a stepped or simulated sine wave UPS. The other feature of the SmartUPS used to be that it had a SmartSlot port to allow for network management cards to be used to monitor and control your power needs... hence "smart"
Yet today its all screwed up.. some SmartUPS units has square wave, All BackUPS have "smart' features that allow monitoring, remote shutdown, etc. SmartSlots are missing on some SmartUPSes and SmartSlots exist on non SmartUPS models.... so what gives?
The bottomline, is that I don't know myself.... but at my store at least I wont sell a SmartUPS that isn't sine wave. That means the crappy SC620 that I got is being sold as a BackUPS 620.
Here are some of the quirks...
Old Smart UPS 700 (SU700) - Sinewave
New SmartUPS 620 (SC620) - Sq Wave
Old SmartUPS 700 - SmartSlot
New SmartUPS 620 - No SmartSlot
New Backup Pro 700 - LCD, Smart controls
