When looking at SQL and NoSQL in back-end development, here are some important differences to keep in mind:

• Structure:
  SQL databases are organized in a specific way. They use something called structured query language, or SQL. This means you have to plan out your tables and how they connect before you start.
  NoSQL databases are more flexible. They can handle different types of data, like key-value pairs, documents, or graphs. You don’t need a strict plan before you begin.

• Scalability:
  SQL databases are good if you want to make one server stronger by adding more power. This is called vertical scaling.
  NoSQL is better when you want to add more servers to handle more data. This is known as horizontal scaling.

• Transactions:
  SQL can handle ACID transactions, which makes it reliable. This means it keeps your data safe and correct.
  NoSQL may give up some of this safety for faster performance and more flexibility.

• Use Cases:
  Use SQL when you have structured data, like in banking systems.
  Use NoSQL for unstructured data, such as on social media platforms.

In simple terms, it’s about picking the right tool for the job!