Arduino was built for the arts community who were already using Processing, allowing them to take what they already knew, and apply it to hardware. That's why it looks like Processing.

Of course, the Arduino board isn't limited to the Arduino programming environment. Hackers tend more towards programming the AVR directly, providing greater performance and environments more familiar to them.

FWIW, it's not "made to look like Processing", it _is_ Processing. They use (or at least built on top of) the Processing IDE.

They are different. Processing is built on Java, Arduino is built on C++.

That's true for the _languages_, but the Arduino development environment is built on Processing, see second para here:

http://arduino.cc/