It is fundamentally, very importantly, different. Being compelled to say / give your password is forcing you to admit or testify that you know the code and can

It is fundamentally, very importantly, different. Being compelled to say / give your password is forcing you to admit or testify that you know the code and can unlock your phone. You can choose not to give testimony (statements) that could be used against you. On the other hand, if you are in possession of a physical key or code written on a piece of paper... or fingerprint... you can be compelled to turn that piece of evidence over to the government.