What is the difference between Mil and Gauge?

As it pertains to Vinyl Pool Liners

Do you want to know what the difference between Mil and Gauge in vinyl liners? We think it was created by some marketing people to confuse us. So we did the asking of the questions with all of our liner porducers and got the answers.

They are both loosely measurements of the liner thickness. A liner that is advertised as a 20 mil usually has a 20 mil bottom and a 15 mil sidewall. A 20 gauge liner means that the liner has a 20 mil bottom and a 20 mil sidewall. So a "Gauge" liner is typically a little bit thicker walled liner than its "Mil" counterpart.

Please check out this chart for further explanation