The difference between them is the Pure Sine Wave inverter produces a better and cleaner current. They are also considerably more expensive. You might find it practical to get a small Pure Sine Wave inverter for any special need you may have, and also a larger Modified Sine Wave inverter for the rest of your applications.
Elm Trees can live over 100 years in their natural environment.
A healthy birch tree should be able to survive and thrive for 40-50 years. In many yards, however, it is not unusual for birch trees, especially the white-barked birches, to die well before reaching 20 years of age.