אל El in Hebrew is Chesed, the Spirit, Innermost, our God.
الله Allah (may He be praised and exalted) refers to "the God," represented by Kether, Chokmah, Binah and Chesed, the light of unity from the Abstract Absolute Space, which cannot be represented in images (and hence it is forbidden to within Islam).
الله Allah (may He be praised and exalted) is broken down as Al-Lah, which is like saying "אל El is אל El," or "God is God." This is why as Muslims we pronounce the Shahada (declaration or testimony of faith), "There is no god but God, and Muhammad is His prophet."
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami