Q: According to Indian philosophy sadasad viveka shakti (the power of discriminating the true from the false) is called Buddhi.
That is not Understanding. Can one discriminate sadasad by Understanding alone or does one require Intellect? It is by what Indian philosophy calls Vijnana that can do it. And Vijnana, in Indian philosophy, is more or less equivalent to Buddhi. Hence Buddhi is Intellect. Understanding only a part of Buddhi.
– Sri Aurobindo