I would think that the gas cloud would spread over a wider area, and being heavier than air would stay close to the ground, thus being more of a danger of a huge fireball.
Gasoline and crude oil, being a liquid at room temp, would stay relatively in one place limiting the damage.................
Methane is much lighter than air. Unless trapped inside a building it quickly dissipates. Methane gas has to be diluted down to 15% concentration before it will ignite. By the time you get significant quantities diluted that much, it is well up in the air.
Much of Gasoline vaporizes into heavier than air gases.
Hydrogen is the one to watch out for with a leak.
It is flammable over a wide range of concentrations, 4% to 75%.
It will detonate at 18% to 54% by volume.
It will detonate without being confined.
It will leak out of the tightest seams and connections.
It is mitigated somewhat by being so light. It dissipates fairly quickly.