What is the difference between queueable interface and future callouts?

Queueable Interface

This interface enables you to add jobs to the queue and monitor them which is an enhanced way of running your asynchronous Apex code compared to using future methods.

Future Callouts

When using synchronous processing, all method calls are made from the same thread that is executing the Apex code, and no additional processing can occur until the process is complete. You can use future methods for any operation you’d like to run asynchronously in its own thread. This provides the benefits of not blocking the user from performing other operations and providing higher governor and execution limits for the process. Everyone’s a winner with asynchronous processing.