I see what you mean here, and it might be what the statistics website is claiming. However, it is not clear at all. They use the words "large share of the smart

I see what you mean here, and it might be what the statistics website is claiming. However, it is not clear at all. They use the words "large share of the smartphone operating systems’ market within the United States," and "largest share of the United States smartphone operating systems’ market" when talking about the market share for Apple and for Android, respectively. Sounds like the same metric is being compared.