Onan generators

5.5 is a lot of generator a 7. 0 is a whole lot of generator. What all do you want to run ?

IIf you are referring to Onan RV generators, they are very similiar.
The 7kw runs at a little higher rpm to make enough horsepower to pull 7000watts.so they use different drive belts and gen pulleys. It also has a larger rotor and stator in gen end. The circuit breakers are usually different also, as 5500 normally has a 30a and 20a breaker, where the 7000 has 2 50a c/b's. the engines and all the mounting base and enclosure are same.

1500 watts or about 12.5 amps. The larger unit will use a little more fuel.

What do you plan to run with the generator? If you give us a little more info maybe we can give you a better answer.

I have a 5000 watt generator in our Southwind, it does everything I need.
If the price difference wasn't too much, I would go with the larger generator. But it depends on what you are running with the generator, how long and how often.

Welcome to the forum.