Inverters offers a long run time (several hours) compared to UPS (5 to 10 minutes)

A UPS is used to keep a computer running for several minutes while the generator starts up (5 to 10 minutes). A UPS will beep continuously when power is off.

An inverter will run for hours and does not beep continuously. It will signal when power fails, when power is restored and when battery is low.

A UPS is cheaper to buy than an inverter.
UPS batteries have a short life span if there are regular power failures, but the batteries are cheaper to replace than inverter deep cycle batteries – usually one or more 12V 7Ah (12V 9Ah)

Neither UPS or inverter are absolutely silent, they have fans that cool the system down when running from the battery.

Maximum run times at different power, and different battery capacities
*Please consider inverter efficiency and maximum battery discharge when reducing the times below.

Watts12V 100Ah12V 200Ah
/ 24V 100Ah
50W19hr 12min38hr 24min
100W9hr 36min17hr 48min
150W6hr 24min12hr 48min
200W4hr 48min9hr 36min
250W3hr 48min7hr 40min
500W1hr 55min3hr 50min
750W1 hr 17min2hr 34min
1000W57min1hr 57min
*run times vary with type of battery, age of battery, ambient & battery temperature, and rate of discharge, inverter efficiency, maximum battery discharge. Example: Note how the amount of power supplied by the same battery drops at higher currents: 10 hour rate (10.0A, 10.8V) = 100Ah. 5 hour rate (17.5A, 10.5V) = 87.5Ah