Arduino and Raspberry Pi are both single-board microcontrollers, but Arduino is designed for interactive objects or physical computing with sensors and actuators while Raspberry Pi is a full-fledged computer. Arduino is an open-source hardware and software company that designs and manufactures microcontroller boards for building devices that can sense and control the physical world. Raspberry Pi is a credit card-sized computer that runs Linux-based operating systems and can be used for tasks like desktop computing, media streaming, and robotics. Some key advantages of Raspberry Pi are its low cost, power, and variety of interfaces, while Arduino is better for interacting with physical inputs and outputs through its input/output pins.