How was abraham different from other ancient gods. Who are they and what was their purpose?

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Ambraham was not God. He was a friend of God, the God of the Bible.

From Wikpedia:

Abraham (Hebrew: אַבְרָהָם, Standard Avraham Tiberian ʾAḇrāhām Ashkenazi Avrohom or Avruhom ; Arabic: ابراهيم, Ibrāhīm ; Ge'ez: አብርሃም, ʾAbrəham) is a figure in the Torah, Bible, and Quran whom Jewish, Christian and Muslim believers regard as the founding patriarch of the Israelites, Ishamelites and Edomite peoples. In what is thus called Abrahamic religious tradition, Abraham is the forefather of these peoples.

According to the Torah, Abraham was brought by God from Mesopotamia to the land of Canaan. This is thought to have occurred around 2000 BC[1]. There Abraham entered into a covenant: in exchange for sole recognition of YHWH as supreme universal deity and authority, Abraham will be blessed with innumerable progeny. His life as narrated in the book of Genesis (chapters 11–25) may reflect various traditions.

If you want to read the rest of the article follow this link:
Abraham - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Abraham)

These too while you are at it:

Abraham (http://www.jewishvirtuallibrary.org/jsource/biography/abraham.html)
CATHOLIC ENCYCLOPEDIA: Abraham (http://www.newadvent.org/cathen/01051a.htm)
Daily Bible Study - Abraham, Man Of Faith (http://www.keyway.ca/htm2002/abraham.htm)