You're right. One of them is professionally produced content, advertised with a preview to whet your appetite, where you're expected to pay for the right to consume it fully. While the other is.... uhh.... the same thing.
When you click a click to a trailer, you know it's not the whole movie.
When you click a click in Google, you don't know if it's paywalled.
How can you not see the difference? It's basic.
Guess that’s the thing. When it shows up in your search result, we do expect it to be ready to read without paying for it. This is partly Google’s fault for not making it easier to exclude paywalled content. Would paywalled content-providers like Google implementing that feature? I doubt it. But also we can use something like 12ft.io.