Generators have been around for quite a while, They consist of an energy source, usually a fossil fuel such as diesel, propane or gasoline, which powers a motor attached to an alternator that produces electricity.
Inverters are a recent development, made possible by advanced electronic circuitry and high-tech magnets. These are generally 3-phase generators that output AC current, but that current is then converted to DC, and then inverted back to clean AC power .
Inverter is used to convert D.C(direct current) into A.C(alternating current).Mainly the inverter is used in UPS.
With a minor difference in construction, a generator can produce alternating electromotive force or direct electromotive force. The corresponding currents produced are called alternating current (AC) and direct current (DC).
Inverter: An inverter is a device which can convert direct current (DC) to alternating current (AC). The inverters used in homes and offices are specially designed to
(I) Convert DC from a battery to AC, and
(II) Charge the battery
An inverter is fitted in the main power line. When there is a power failure, the inverter automatically switches on the AC, converted from the battery's DC, for lighting and running electrical gadgets. When the main's supply is restored, the inverters automatically switches to a made where it starts charging the battery depleted due to use during the period of power break-down.
Generators are a long-standing invention that is powered by fuel, and investers are completely different, new. They are more like energy converters, in a sense. I don't think I'm very good at explaining things. You should read more detailed information here if you are interested in this topic. I think that you will find the answer to your question.