The Buddhist chakras, except for a few specific tantras, are described as five in nature. You would naturally expect them to stack up according to their hierarchy, their density, their sequential refinement, just as in the Shaivite approach and their hapless inheritor, the Western New Age chakra system. After all, that is how humans seem to be built. The vertical stack of human anatomy is our natural, biological makeup as our form and function span the gamut, from earth to sky.
But the tantric path is about building a new body, a new form, one commonly referred to as a light body or rainbow body. The meditations we superimpose (the spiritual stack) on our normal bioenergetic hierarchy (the biological stack) are revolutionary.