A library catalogue lists the resources you will find in the library's collections.
An online catalogue is called an OPAC. This stands for Online Public Access Catalogue. It allows you to search for information in many ways, including by author, title, subject and keyword.
The library catalogue is always a good place to start a search.
A bibliography or reference list, is how you acknowledge the author's work you have used to write an essay or an assignment.
A bibliography generally lists all of the works you have used to generate your ideas about the topic you have been asked to research. This allows you to not only list the works you have cited in the body of your assignment, but you are also able to list any other resources you looked at to learn about your topic. You would create a bibliography if using the Oxford or Traditional Note referencing system.
A reference list usually only contains the sources you have cited in-text in your assignment. You would use this if you are using either the Harvard Referencing system or APA. MLA also adopts this approach, that is the works cited list contains the material referred to in your assignment.
An index is an alphabetically arranged list of the headings or topics that appear in a published work. An index will also provide page numbers that point to the area of the work that you need to go to.