According to Islam, Abraham moved Ishmael and his mother to a barren valley, following the command of Allah. This valley would eventually become the city of Mecca, partly due to the Spring of Zamzam which gushed forth from a spot where Ishmael had kicked. Some of the rites of Hajj (pilgrimage) commemorate the actions of his mother, Hagar, in her search for help. In Islam, Abraham and Ishmael built the Ka'bah, the structure that all Muslims face towards in prayer, to be the first house of worship for the One True God.
A major difference between Ishmael and Isaac is that Muslims believe that Ishmael was the one that Abraham was commanded to sacrifice, not Isaac. Abraham saw in a dream that he was slaughtering his first born son, Ishmael, from his second wife, Hagar. Judeo-Christian sources tend to suggest that Isaac was the first born and that Hagar was not his wife. However according to these same sources, Sarah gave her servant, Hagar, to Abraham as a wife. Also, Ishmael would still be considered his first born. So if Isaac would have been sacrificed, Abraham would have had yet another son, lessening the impact of the act.
Besides the above there is not much difference because there is not much mentioned in Judeo-Christian sources about Ishmael. In Islam he is a prophet and son of a prophet (Abraham). According to some sources, Prophet Muhammad descended from his lineage. Islam describes Isaac as a prophet, son of a prophet (Abraham), father and grandfather of prophets (Jacob and Joseph, respectively). In Islam, all the prophets are held in the highest of esteem and we only accept that which is in agreement with the Qur'an and narrations of Prophet Muhammad, so much of the details that are mentioned in Judeo-Christian sources cannot be affirmed or denied.