MongoDB is what is known as a document database, which means that its approach to data management is geared towards working with rich documents with multi-leveled schema. That doesn't mean we can't use a document database for the same sorts of data we might expect to see from a traditional relational database, but it's important to note the differences in how that data is composed within the database.
For example, two different tables in a relational SQL database might simply be best represented as a single document in a document database:
One of the main distinctions between a NoSQL document database, such as MongoDB, and a traditional SQL relational database is the manner with which relationships between documents are managed. Relational databases traditionally use JOIN operations to merge normalized tables of data together as part of a query operation...