Saguna and Nirguna Brahman
Brahman with qualities and without qualities.
Saguna Brahman is the qualified aspect worshipped as Ishvara (God with form). Nirguna Brahman is the unqualified absolute beyond all attributes. Both are perspectives on the same reality.
Higher than this is the unmanifest, higher than the unmanifest is the Purusha.
This distinction allows for both devotion and transcendent realization.
Katha Upanishad