SQL databases are relational, NoSQL are non-relational. SQL databases use structured query language and have a predefined schema. NoSQL databases have dynamic schemas for unstructured data. SQL databases are vertically scalable, NoSQL databases are horizontally scalable. SQL databases are table based, while NoSQL databases are document, key-value, graph or wide-column stores. SQL databases are better for multi-row transactions, NoSQL are better for unstructured data like documents or JSON.