An Electronic Journal (or E-journal) is a traditional journal that is in an electronic format; either because it was originally created that way, or because someone took a print journal article and scanned it to make it available electronically.
A Database is what is created when a large number of electronic journals are put in one place and a search interface (usually a search box) is added to help find what you need. Both databases and electronic journals can be subject specific. When you have a database that only has the title or abstract, but not the full text, it is usually referred to as an Index.
