Let's cover some of the differences between a relational storage model and a key-object storage model, because although both the storage models seem similar initially, they are, in reality, very different. As such, you may choose to use both in your application if some of your data is better stored and queried using the relational model while other data more closely fits the key-object model.
The relational storage model simply describes relationships between data described at the schema level. A schema describes the fields in a data structure. In relational storage models, schemas are also often called tables.
Tables store data as a series of rows and columns, somewhat like a spreadsheet, except that the rows and columns aren't numbered in the same way (for example, a spreadsheet typically names columns with sequential letters and rows with sequential numbers). The relational component itself describes how one data in one table relates...