Thermal Underwear vs. Long Johns

One year ago, I suggested my friend bring his long johns on a trip to go mountain skiing, to which he replied, "No way! I'm taking my thermal underwear." And I said, "Okay!" I explained that this is a long john, but he insisted that it is "thermal underwear."

From that day on, I have been trying to figure out the differences between Long Johns and Thermal underwear. At first glance, I see them as separate entities, but how are they different? You must also be wondering!

Thermal underwear vs. Long johns

I did my research and visited dozens of forums online, and realized a few things. People's perceptions of this underwear, and what they think is the real difference, were influenced by these factors.

We can start by trying and seeing what we can find, so let's begin!

Here are the main points.  The term thermal underwear is perceived as a general term by most people. However, some people believe that it is made from a specific fabric.

Additionally, the term "long johns" may seem colloquial or funny to some, whereas "thermal pants" may sound more appropriate and exciting. Nonetheless, these two terms are interchangeable, meaning they are related in some way.
According to most Californians, the term "thermal underwear" is the best way to describe it.

The material used in the construction of the two is now used to distinguish them by some. According to some, silk underwear is long johns, while thermal underwear is made with a "waffle" material.

What type are you? Which is right in your opinion?

Both are the same, even from the designers' point of view. Therefore all of them are thermal underwear. As for the tops, you could wear a thermal undershirt or thermal bottoms, depending on the weather.

Despite this, some believe the term "long johns" refers only to the bottoms. You can also call it long underwear if it covers both tops and bottoms. Do you think it's true or just a perception?

Additionally, 'long johns' is considered by some as an explicitly male garment. The tops will be thermal shirts since it refers to the bottoms. A long john seems like an outdated name, so young people may not often use it.

The word "underwear" remains the same for women, but the term "shirt" may vary depending on its use. Another name for a top that ladies often use is "thermal Henley."

However, it seems that the names (thermal underwear and long johns) might be a generational thing. It appears that over-40-year-olds are only familiar with the phrase "long johns," which is just because under-40s rarely say it. However you choose to call them, they all stand for the same thing, but it's nice to know more than one name.