Panasonic Microwave Ovens with Inverters Technical Manual page 8

Traditional microwaves send out a single level of power in small bursts to cook
food at different speeds. For example, when set at 60% power, the microwave
energy would be on 60% of the time and idle 40% of the time.
Inverter microwaves, however, give accurate, true multiple power levels. When
you ask for 60% power, the oven delivers 60% power (e.g. they don't just operate
60% of the time). This applies no matter what power level is selected. True
power levels give you better cooking results and your food would have an even
texture and temperature after cooking. The constant soft penetration of
microwave energy into the center of the food helps prevent overcooking on
edges and surfaces.
Difference Between Pulsing and Linear Power Control
Power Level Comparison
Figure 1
Figure 2
3