They key to identifying sponsored content, is looking for the disclosure. Under FTC guidelines, sponsored content has to be obviously disclosed and identified by a reasonable person.
In the header, you are looking for a logo or a paid for by.
Pre-click, on a feed, near the headline should be a brand logo.
If you haven’t found these, it’s not likely to be sponsored content.
Why is disclosure important?
It’s important that consumers know when something is an advertisement, also for the brand, it’s in their interests to have brand recall associated with the content.
Where is the best place to disclose?
A Nudge study, showed that the disclosure has to be in the content, whether it’s in the title or the beginning of the content. As a users eye is naturally drawn to that part of the content. You can read more here: Which native ad disclosed itself best?