Every organization will have both structured and unstructured document with which to contend. It is generally a good idea to purchase a document imaging system that offers the maximum capabilities to deal with both types of documents, rather than purchasing a system that caters only to a single document type.
What is the difference between structured and unstructured documents? With a structured document, certain information always appears in the same location on the page. For example, in an employment application the applicant's name always appear in the same box in the same place on the document. In contrast, an unstructured document has the opposite characteristics - information can appear in unexpected places on the document. An example would be in a hand written note or a whitepaper.
Some documents share the characteristics of both types of documents, such as invoices. For example, suppliers' invoices feel like a structured document because they have a consistent appearance from one billing period to the next. However, when viewed in aggregate by an accounts payable department that receives thousands of invoices daily in a myriad of different formats; they seem more like structured documents.