There are lots of ways to deal with the differences, ranging from very simple to very complex.
Simple is to use a transformer to get 110/220 from 220. The own side is that it doesn't convert the frequency form 50 to 60 hz. Some appliance don't care and will work fine on either, but others won't. With a simple approach like this, the intolerant appliances either don't get used, or must be run off your generator. There is another complexity to this that most people ignore, which is that when you run a 60hz motor on 50hz power, you need to also cut to voltage accordingly. So a 240V 60hz motor should be run at 200V 50hz. If you read the fine print on motors, AC units, etc., they will typically say this, but not always. Ignoring it won't cause things to go up in flames, but it stresses the motor beyond it's design intent.
Slightly more complex is to use an inverter to power your 110V 60hz loads, then use a big battery charger that will accept 230V 50hz power input. Other devices that are happy with 50hz can be run directly off shore power. Some people also go a step further and run some of the 240V devices off inverters as well. It works well, but you just need to be sure your chargers are large enough to keep up with the load.
The most complex, and easiest to use, is an Atlass or ASea unit. They are conceptually the same as the back to back charger/inverter above, but able to take in pretty much any form of shore power and turn it into whatever you want on board. They cost $$, take up a lot of space, and generate a lot of heat, so typically only appear on larger boats.