Sanpo-yoshi Communication
Liner refers to the paper used to make corrugated board. Corrugated board is a very environmentally friendly packaging material with a high recycling rate.

The person in charge of text on the company's website asked, "Marushin's website is labeled [Liner], but the website of the National Federation of Corrugated Packaging Industry Associations is labeled [Liner]. Is this a typographical error? I only said [liner]. I had only ever used the term "liner," so I checked the website of the National Federation of Corrugated Industries Associations and found that "liner" was indeed used in the explanation (oh no, I may have misspelled it). Next, I searched for [liner] and found that many corrugated companies use [liner] (a relief).
When I compare the recognition and use of a word, I do a computer search and compare the number of information about it. I compared the number of cases for the following search terms

The use of the term "liner" seems to be slightly more common. We also found that the explanations for both [liner] and [liner] are the same. Next, we contacted two corrugated packaging companies with whom we do business. The results were as follows,

The answer was "I have never heard of [liner]. So I wondered if I had only heard of [liner], but I was curious to know what kind of places use [liner].

In the end, since different manufacturers call it by different names, it seems that the notation used by the base paper manufacturer affects the way it is said by the corrugated fiber manufacturer. In other words, both are correct.
Incidentally, Teijiro Inoue (1881-1963), who is known as the father of Japanese corrugated board, is also the godfather of corrugated board and founded the largest corrugated board company in Japan. Since that company uses the term "liner" in its name, we have decided to use both names in our company, imagining that perhaps the name "liner" was first called "liner" and then "liner" was passed on by hearsay (^^).
Words are interesting. In memory of Teijiro Inoue, who developed the cardboard, I thank the person in charge for asking interesting questions.