ARDUINO is like a car brand. There are high-end cars and low-end cars. You can drive it if you buy it. Just because you can make the car run doesn't mean you know how the engine works. ARM is similar to a kind of gasoline engine, with good performance and poor performance, but in short, they all burn gasoline. (Some of arduino's cars also use this kind of engine.) Raspberry pie and arduino are similar to their cars, which use ARM's high-end engine, such as a power output device. . There are gasoline engines that burn gasoline (many chips of ARM can also be included in single-chip computers), many steam engines that use steam (such as the most common mega.805 1, etc.), and many of them are not as good as steam engines. Arduino is a development environment, which can develop platforms such as avr.stm32.esp8266. 5 1 is a platform that can be developed with keil and other development environments. Arm is an architecture. Raspberry pie is a small linux computer.