Do you mean other forms of database? A database usually means an organised and structured ("ordered") storage of data, such that information can be extracted from it in a consistent and repeatable way.
A relational database will often store different sorts of, but related to each other, data. The relationships are stored along with the data. So you can extract much more (and usually more useful) information, using the correct software, from a relational database than a mere ordered set of records. All commercially (and open source) database packages these days are RDBs
