Currently there is a define for the board type -DARDUINO_{build.board} that is passed to the compiler.
But the actual name of the board as a string is not available.
There are some use cases in diagnostic tools where having the actual name of the board as a string can be useful as it can be used to display to the user.
The esp8266 core uses this define -DARDUINO_BOARD="{build.board}" in their platform.txt file.
It would be nice if the Arduino.cc provided cores supported a define that allowed the code to obtain a string version of the board name.
Since the name ARDUINO_BOARD is already used by the esp8266 core, perhaps the Arduino.cc cores could adopt the same thing.