Ubuntu Listed by Itself on NetMarketshare?

Today I decided to check on NetMarketshare's stats from last month and noticed something that caught my eye:

If you see the last entry, it reads "Ubuntu: 0.63%."

The curious thing is that, 3 lines above, you read Linux at its never changing one point something market share, according to the site, that is. Although, compared to July, when Linux had 1.29%, August's 1.38% is quite a leap.

But why is Ubuntu listed separately?  The page is listing desktop operating systems, so I see no need to separate Ubuntu from all the other Linux desktop distros.

If Ubuntu's share were added to Linux, then the penguin's market share would be 2.01%.

Or am I missing something?  Is Ubuntu using a kernel different from the Linux kernel, for example, and became a totally separare OS?

I guess I have to check that out. 🤔