The types of Digital Libraries: don´t be worry, is really more o less the same from you since your seat in your home.
But finally all of them have documents, in those cases you can call them Digital Document, but remember that firstly are documents , it isn´t? so don´t be worry about the names “Virtual Library” or “Digital Archive” or bla, bla, bla…
Only if you think that there could be something interesting for you, try it out and find it out! Is the only way to do this kind of things.
It is the reason because I include the Digital Archives, Academic Repositories and Digital Museums here. Because all of them are offering us documents, and the Libraries are composed of this documents, so we could surfing this website as the same. Obviously everyone has a specific definition and borderline, but it is not really interesting for a researcher.