Absorption fridges are known as 3-way fridges because they can run on either 12/24-volt, 240-volt or LPG gas. Instead of a compressor, a 3 way fridge uses a gas flow heat exchange system in the back of the fridge. Essentially they remove the heat rather than create the cold.
Thanks to the more powerful compressor motor, compressor fridges can provide more consistently cool temperatures even in very hot environments – which makes them the perfect choice if you are heading into warmer Australian climates. This means most compressor fridges can even double as freezers. Absorption fridges can't get as cold in hot environments
Absorption fridges have the edge here, as they will often only need replacing after 20+ years, compared to around 10-15 years for compressor fridges. Of course it depends on which model you choose and how well you look after your caravan fridge.
Compressor fridges are built with 12-volt operation in mind, so they run far more efficiently on DC battery power than absorption fridges. That said, absorption fridges are extremely efficient on gas. This is where these types of caravan fridges are very popular; if you intend to free camp for longer periods then running your 3 way fridge on gas can last you around 2-3 weeks on a 9kg gas bottle
Because absorption fridges use a heat exchange system rather than a compressor, they don't make a sound. The opposite is true of compressor fridges. Think about the noise that comes from your home refrigerator, and although your caravan fridge isn't running all the time, it will still be audible when the compressor is running. The good news is most quality caravan compressor fridges today are still quiet.