natural gas comes in a gas main line / pipe whereas propane is delivered as compressed / liquefied and stored in pressurized tanks.
nat gas is by far the preferred choice because it is 1/2 the price of propane but not all locations have access to a gas main, so most remote locations have propane tanks instead.
its basically the same as sewer vs septic tank. public sewer is better because it will work forever and you can flush down anything you want but not all locations have access to public sewer because shit can only flow downhill and in flat areas like Florida septic tanks are more common.
but real estate agents are salespeople and salespeople are professional liars, so if the home has a septic tank they will say it’s good because you don’t need to pay ( peanuts ) for the public sewer. yes you save a few bucks then you need to spend thousands when your septic fails.
likewise if home has propane bottle real estate agents will tell the lie that propane is “more energy efficient” … this is the standard industry lie. what they refer to is that propane is twice as dense as natural gas so you need half the volume of propane for same heat vs natural gas. but that has nothing to do with “efficiency” - it’s a matter of density. all “high efficiency” furnaces have about the same efficiency of about 95% regardless of whether they run on nat gas or propane.
real estate agents simply exploit the fact the average American doesn’t know physics and instead of saying propane is more dense say it’s more energy efficient, which is a lie … but they all say it to sell the home.
of course propane is actually far LESS efficient, because you need to use energy to first distill natural gas into propane, then deliver it using a truck … and of course the tank can burst potentially killing anybody nearby.
i had to write this up because even unbiased articles on the subject are written by people with no understanding of physics and regurgitate the “propane is more efficient” lie because all the average person can do is repeat what they’re told.
always try to get a home with natural gas line if you can. you can use it to heat your home, cook your food and also to run a generator in case of power outage.
propane can also do all that, but it will cost double.