Referral traffic is the segment of traffic that arrives on your website through another source, like through a link on another domain.
Google Analytics sorts referrals in the Acquisition report. However, there is an issue with the way it credits referrals sources.
For example, if a user comes from Yahoo to a certain article (article A) on your site and then moves to another article (article B) on your site, both of these articles would have Yahoo as their referral source. These articles were viewed during a single session and Google Analytics recognizes only one referral source (i.e. the one that brought the visitor to the website).
In Content Insights, in the same scenario, Yahoo would be the referrer for Article A, just like in Google Analytics. However, for Article B, Article A would be recorded as the referrer.
There is a reason why we designed our analytics solution so that it recognizes all referrers, as the user navigates through the website: Content Insights is the content analytics solution, which means that we look for the cause of the user action on the content level.
Google Analytics is focused on helping e-commerce businesses, not publishers. This is why it only offers a top overview of the external sources of traffic. It does not track the actual path of the visitor/reader on the site itself. This can be useful for tracking conversions but has little editorial value.