Two-way fridges run on electricity, three-way car portable fridge freezer can run on either electricity or gas. So which is better?

Two-way (compressor) portable fridges
Two-way fridges use the same compressor technology as your home fridge, though they're designed to run on a 12-volt battery as well as mains electricity. They're best for most applications because they're designed to run off your car's electrical system without drawing too much current, but can be switched to 240 volts in powered campground sites or in your home.

Unlike gas fridges, compressor models mean regular battery charging so they may not be the best choice for a month in situ, but they'll tick along happily with a small solar panel setup.

Pros
Good performance, even in hot cars and high ambient temperatures.
Some can double as freezers.
Work on uneven terrain or inclines.
Can be run from a solar panel for out-of-vehicle use.
Designed for efficient, low current draw running off your car battery.
Cons
Setting a consistent temperature when ambient temperatures change can be tricky.
Compressor noise may be noticeable in quiet campsites.
Batteries must be charged regularly or your car electronic refrigerator will stop.
If running off solar, it will turn off overnight.
AC adaptors may need to be purchased separately.