Catalogues list the book- and journal-stocks of one or more libraries. Here you can identify book sites as well as their signature, in order to access certain media. Catalogues generally do not record articles from journals or collective work.
How do I search for articles from sport scientific journals?
Where is this specific title located in Münster?
Here you find some assistance regarding the different search options.
Databases generally list discipline-specific literature. Here it is possible to thematically search for journal articles or papers from collective volumes. After the thematic search there follows (often times automatically) a catalogue search for the sites of the identified books and journals.
Search portals provide the opportunity to research both catalogues and databases simultaneously. This research is generally automatically expanded by checking for availability of the identified documents.