I would like to know the difference between Ishwara and Brahman. If Ishwara is saguna rupa of Brahman then is it real or maya?
Here is the answer directly from Sri Shankara's commentary on the Brihadaranyaka upanishad -
Therefore the unconditioned Self, being beyond speech and mind, undifferentiated and one, is designated as ‘Not this, not this’; when It has the limiting adjuncts of the body and organs, which are characterised by ignorance, desire and work, It is called the transmigrating individual self; and when the Self has the limiting adjunct of the power of (Māyā manifesting through) eternal and unlimited knowledge, It is called the Internal Ruler and īśvara. The same Self as by nature transcendent, absolute and pure, is called the Immutable and Supreme Self.
In the real or Paramarthika sense, only Brahman exists which is one with Atman.Brahman is realised when there is no difference between jnana, jnata and jneya.This is called Triputi-Veda. There is no sense of I, the World and Brahman separately. This stage is attained when the mind dissolves completely in Brahman.
But so long as there is the feeling of 'I', there is some sense of the existence of the world and the controller of the world. Ishvara is the controller of the world, He/She is the Saguna Rupa of Brahman ie Brahman perceived through the veil of Maya (Creation-Preservance-Destruction are the activities of the three gunas :Rajas-Sattva-Tamas and hence of Maya as Maya is Trigunatmika).
So long as the sense of a separate 'I' is real, Ishvara is also real. Only when there is no longer a separate identity of 'I', Brahman alone exists. That is the Paramarthika stage,There is no existence of the world and so no existence of the controller of the world or Ishvara as separate from the Self.
So Ishvara is always existing except at the Nirvikalpa-samadhi state.
Reference: Vivekanander Vedanta-chinta, Dinesh Chandra Bhattacharya Sastri, RMIC, Kolkata.