To the extent that classical training is about 'flawless performance' and jazz 'training' is about 'fluid improvisation', in my experience these are very differ

To the extent that classical training is about 'flawless performance' and jazz 'training' is about 'fluid improvisation', in my experience these are very different skills. The question is: how does such a study decide whether the 'brains ... work differently' because the tasks are so unalike, or because the brains themselves are somehow different. Another question is proficiency: clearly 'virtuoso' pianists are different from 'amateurs' on both sides of the aisle. Are the brains of the 'virtuosos' more 'different'?