These refer to two main categories of portable fridges. A two-way portable fridge runs on a compressor type of energy while a three-way fridge runs on absorption. A compressor is the same as what regular refrigerators use — in a two-way fridge, it can run on 12V battery or main electrical sources. This means that you can use your car or truck’s battery without worry about sucking your vehicle dry of its energy. Three-way fridges can do all of the aforementioned with an addition to running gas. Most campers rely on three-way fridges during longer camping trips due to the long-lasting energy three-way refrigerators run on (lasts for a couple of weeks). Plus, being powered by gas produces less noise too.