Advaita (अद्वैत) & Vishishtadvaita (विशिष्टाद्वैत) are the most popular schools of Vedanta.
Both systems teach Advaita, i.e., non-duality or monism. There exist not several fundamentally distinct principles, such as the Prakriti and the Purusha of the Sankhyas, but there exists only one all-embracing being. While, however, Advaita taught by Sri Sankara is a rigorous absolute one, Sri Ramanuja'* doctrine has to be characterised as Vishishta Advaita, i.e., qualified non-duality, non-duality with a difference.
According to Sankara, whatever is, is Brahman, and Brahman itself is absolutely homogeneous, so that all difference and plurality must be illusory.
According to Ramanuja also, whatever is, is Brahman; but Brahman is not of a homogenous nature, but contains within itself elements of plurality owing to which it truly manifests itself in a diversified world.
The world with its variety of material forms of existence and individual souls is not unreal Maya, but a real part of Brahman' nature, the body investing the universal Self. The Brahman of Sankara is in itself impersonal, a homogeneous mass of objectless thought, transcending all attributes; a personal it becomes only through its association with the unreal principle of Maya so that strictly speaking Sankara' personal , his Isvara, is himself something unreal, Ramanuja' Brahman, on the other hand, is essentially a Personal **, the all-powerful and all-wise ruler of a real world permeated and animated by his spirit. There is thus no room for the distinction between Parama Nirguna and an Aparama Saguna Brahman, between Brahman and Isvara.
