SQL : One type (SQL database) with minor variations
NOSQL : Many different types including key-value stores, document databases, wide-column stores, and graph databases Schemas ——- SQL: Structure and data types are fixed in advance. To store information about a new data item, the entire database must be altered, during which time the database must be taken offline.
NOSQL: Typically dynamic. Records can add new information on the fly, and unlike SQL table rows, dissimilar data can be stored together as necessary. For some databases (e.g., wide-column stores), it is somewhat more challenging to add new fields dynamically.