Many great and wonderful look alike boards have been designed and manufactured since the beginning of the project.
Although there is nothing wrong with using Arduino for commercial purposes, some suppliers have chosen to produce boards without giving credit to the original designers. This is not ideal because open-source software depends on acknowledgment of work added to an idea.
The form factor of the Raspberry Pi computer is similar to that of the original Arduino-Uno. The Raspberry Pi was created many years after the Arduino and uses a more powerful chipset. The Raspberry Pi is, effectively, a fully fledged computer capable of running Linux.