Circuit Playground started its life as a board with simple requirements - just work with Arduino IDE and Code.org. But since it's initial launch in 2015 we've learned a lot and improved the board greatly!
There are TWO Circuit Playgrounds - one Classic and one Express.
The Classic version can run Arduino and Code.org
The Express version can run MakeCode, CircuitPython, Arduino, and Code.org CS Discoveries.
Older Circuit Playground Classics didn't have the word Classic on the back, but they do have text that says the chip type, ATmega32U4