Isabel is a variant of the name Elizabeth (Hebrew) and is of Spanish origin. The name basically implies devotion to God and the fulfillment of a promise and means God is Bountiful or God of plenty as also God's promise.
Eliza is a Biblical name, not a Muslim one. Eliza is a Christian name, and comes from the Bible. Another answer: "Eliza" is a shortened form of Elizabeth, which is Hebrew in origin and means, "oath of God." The only Elizabeth in the Bible is the mother of John the Baptist (Luke 1:13).