The Recommended Content widget, or related content, is a convenient way to provide results that are similar to the item you are currently viewing.
Why searching for a term via site search won't return the same results as seen in the Recommended Content widget
In site search, you are searching against the text you have entered.
This is not the same as the related content results. With related content, the results are produced by taking the contents of the item you are currently viewing and generating a search based off of that. This can produce widely differing results between the related content widget and results from a manual search.
Recommended Content makes use of Solr's MoreLikeThis handler. It takes the first 25 terms that occur in the most docs and compares them. Post title, post body & attachment text and tags fields are used in the comparison.
Fields used by Recommended Content
- Post title
- Post body
- Attachment text
Using Recommended Content
The REST documentation for consuming the Recommended Content can be found here.
The widget configuration is here.