“And God spoke to Moses and said to him, I am Adonai, I appeared unto Abraham, and to Isaac and unto Jacob as El Shaddai- But my (Real) name of Adonai I had not yet revealed to them.” (Exodus 6:2-3)
God had a certain relationship with the patriarchs that it was different than the relationship with Moses. Perhaps it was more distant, now, the newer and more tentative way God describes self speaks of in a more respect form. The Patriachs knew El Shaddai, the powerful God. Moses is ready to know Adonai-the mystical four letter name. According to Midrash is the God of mercy, Midat Rahamim which balances Elohim, the strict justice aspect of God. With the suffering of slaves there was a need for a compassionate God who hears their claim. We should still understand the many aspects of God speaks of ONE GOD but admits a variety of ways to conceptualize and approach the Almighty.