God and Lord God refer to the same thing. In heaven, names change depending on circumstance. For instance, before the fall, the devils name was Lucifer. After the fall, he is Satan. Before becoming human, the Son’s name was Michael (He who is what God is). Then He was foreshadowed as Emmanuel (God with us). Then He was Yahushua (Yaweh the savior) who we now call Jesus. It’s also written that after the second coming, the righteous are given new names. This is because we will no longer be fallen beings but restored to the heavenly family. As for the trinity, there is God the Father, God the Son, and God the Holy Spirit. All are their own person yet all are still God. They are co-equal beings that are all God and are in perfect union with one another. God exists in this way due to the way love is expressed. Heavenly love “agape” is selfless and cannot be expressed as a single individual. Before creation, there was just God so He had to exist as multiple entities in order to express love because He is love and existence.