Let's first agree that "x is not y, but rather z" supposes that x, y and z are of the same logical category (as in: cats are not oviparous, but rather viviparous)
Perhaps then we can agree that "x is not y, but rather (of)/ a kind of z" is wrong? (as in: cats are nor oviparous, but rather (of)/ a kind of viviparous animals, something that describes a viviparous category).
Can something be a A KIND OF something else (as opposed to just - what appears logical - something else? how could these also be parallel - logically and grammatically?
I see this on VR2nd edition (the correct answer is given: x is not a reactor but rather a kind of battery).
Thank you!