He definitely thinks there’s a substantive difference: if reason is a sense, and all our knowledge comes from the senses (including reason) then all our knowledge is a posteriori. Rejecting the mechanism of a priori knowledge acquisition is rejecting rationalism (regardless of how the word ‘rational’ mutates in the mean time).
I would say it’s more like novalis thinks there is no substantive distinction between empiricism and rationalism.
He definitely thinks there’s a substantive difference: if reason is a sense, and all our knowledge comes from the senses (including reason) then all our knowledge is a posteriori. Rejecting the mechanism of a priori knowledge acquisition is rejecting rationalism (regardless of how the word ‘rational’ mutates in the mean time).