What Is the Difference between Structured and Unstructured Information?
The term structured information describes the data contained in fields. It is called structured because its nature and function are identified by metadata tags. All content created
directly within SharePoint (ex.: list items and area listings) is structured. Whereas,
the term unstructured information describes binary documents (ex.: .pdf and .docx documents) added using proprietary applications such as Acrobat or Word. SharePoint
references are used only to index structured information; unstructured information
is automatically extracted using the corresponding converter or IFilter.