What is the difference between Brahman and Ishwara? Who is Datta?

Brahman is pure awareness. You can attain peace and bliss by ‘becoming’ Brahman, which is yourself. If you detach from the body and feel that you are Brahman you can attain peace and bliss. But you should remain in peace and bliss thinking that you are pure awareness even if you are beaten in hell. Such detachment is essential. Ishwara means Lord Datta who appears peaceful and as if He has bliss. He donates His peace and bliss to His devotees and does not enjoy the peace and bliss internally. The the Veda says the same (Esha Hyeva Anandayati). Datta means sacrifice and not enjoyment. He takes the fruits of all the sins of His real devotees and is an ocean of unhappiness internally. He alone can come as a human incarnation in this world. Every living being is Brahman because the pure awareness is present in any living being. The peace and bliss are attained only by the grace of Ishwara, even in this stage of self-knowledge as said by Shankara (Ishwara anugrahat eva…). Otherwise you can become just the pure awareness by Advaita [the knowledge that you are the pure awareness]. But the pure awareness will be associated with peace and bliss when you are sitting in meditation by the grace of Ishwara or may be associated with unhappiness and disturbance while you are beaten in the hell. Therefore Ishwara is the final goal and not Brahman, since Brahman is already achieved by any living being.

Even a worm in the drainage water has already achieved the Brahman. The path towards Ishwara is full of sacrifice because the very nature of Ishwara (Datta) is sacrifice. As you achieve more and more sacrifice you practically become Datta more and more.