What is the difference between rabb (lord) and ilaah (god)?

The word ilaah (god) is comprehensive whilst the word rabb (lord) is more specific. Ilaah includes all of the god's names, attributes and characteristics and it is this god alone that mankind is expected to serve. It appears in the shahadah (testimony) Muslims pronounce "There is no god but Allah". The term is used 120 times in the Qur'an of which 37 occasions refer to a false god: “Your god (God) is the one god (One God), there is no god except Him, the All-beneficent, the All- merciful.” (2:163) "Allah the High and Sublime states: Verily Allah is the One and Only Deity (Ilaahun Waahid). Far Exalted is He from having a son and to Him belong everything in the heavens and the earth and Sufficient is Allah as a Caretaker. [Soorah An-Nisaa, Aayah 171] “Were you witnesses when death approached Jacob, when he said to his children, ‘What will you worship after me?’ They said, ‘We will worship your god (God), and the god (God) of your fathers, Abraham, Ishmael, and Isaac, the one god (One God), and to Him do we submit.’” (2:133) The term rabb refers to lord it can mean master, guardian or even owner. It refers to the one who nurtures and sustains all of his servants through regulating their affairs and granting them his favors and blessings. This is why their duas (prayers) are made using this term or one of his names when people seek support, guidance or nurture. It is used 963 times in the Qur'an: "And your Lord is Most Forgiving, Owner of Mercy. Were He to call them to account for what they had earned then surely He would have hastened on their punishment. But they have their appointed time beyond which they will find no escape." (18:58)