It's fairly similar, but the Gameboy CPU supports a few opcodes that the E-Reader doesn't (DAA, HALT, DI, EI) and the E-Reader has a few custom opcodes (there's

It's fairly similar, but the Gameboy CPU supports a few opcodes that the E-Reader doesn't (DAA, HALT, DI, EI) and the E-Reader has a few custom opcodes (there's a couple for waiting a specified number of frames, and a couple used for API calls). I think it's better to say that both are 8080 supersets.