Excerpt from the Ingeniux: evaluation:
"Note that Ingeniux stores and manages content as XML within a file system (rather than a database). You can optionally use a database for faster indexing and search of the content, though not for the management of that content. In practice, this "pure XML" approach means you need to take special care in modeling content structure up front, including schemas for validation. In this respect, the product differs from other file-based content management systems, like HP, that will enable you to manage unstructured (or at least, not as well-structured) files, such as HTML. ..."(P. 399 in the Web Content & Experience Management Report. )
Content Management System
When you start looking deeper, some significant differences emerge.