They're not the same.
Natural gas is composed of a few different things like butane methane even propane and a few others.
Propane is just propane.
For environmental purposes, propane is cleaner than natural gas.
I don't think the article distinguished the two.
I'm okay with that if they're willing to stone themselves to death for adultery as well.
Usually the people who want to stone others don't want themselves included in the stoning.
I'm sure there's a high percentage of adulterers in that group.