The difference between a smartphone and a tablet is the size and capabilities of the device. Smartphones are typically smaller than tablets, with screens that range from 4-6 inches in size. Smartphones are designed for portability and are typically used for making calls, sending messages, and running mobile apps. Tablets, on the other hand, are larger than smartphones, with screens that range from 7-12 inches in size. Tablets are designed for both portability and productivity, and they are typically used for web browsing, multimedia consumption, and running mobile apps.