A gas balloon is completely enclosed and is filled with helium or hydrogen. A hot air balloon gets its lift from heating the air within.

Hot air balloon flights usually last about an hour, while gas balloon flights can last for days. Gas balloon flights require much more preparation and equipment for cold weather, high altitude, and night flight. Gas balloonists also pack enough food and water for several days.

The Breitling Orbiter, which flew non-stop around the world in 1999, was a combination gas and hot air balloon.