Vijja. Vijja is the pure Knowledge derived from enlightenment through the insight of Dhammakaya
Dhammakaya (or Dharmakaya in Sanskrit) is the body of enlightenment. Dhammakaya is the real being of Buddha (Buddhabhava) with all the 32 marks of a Great Man. Since Dhammakaya is the body of enlightenment, it accommodates all the enlightened Knowledge (called the Dhamma), part of which was taught by Lord Buddha during his time.
Hence, Vijja Dhammakaya is the pure knowledge derived from the enlightenment via the Dhammakaya which is the body of enlightenment.
Dhammakaya is not a new theory or discovery. On the other hand, Dhammakaya is the original teachings of Lord Buddha.