In an attempt to represent the Hebrew term for God in the Bible, scholars have taken to using English words with different capitalization. In addition, different translations use the terms in different ways. To make matters worse, translators have tried to respect the Hebrew tradition of not spelling out God's name. Here are a few of the terms used in the Bible and what they refer to in the original Hebrew.
What is the difference between LORD, GOD, Lord, God, etc. in the Bible? What does each mean?
LORD or LORD: This spelling is usually used when God's proper name is meant. The Hebrew, without vowels, is YHWH. Other translations are Yahweh or Jehovah.
Lord: "Lord" or "lord" in the Old Testament merely refers to someone of a higher rank (Genesis 18:12), including the pre-incarnate Christ, if the speaker isn't aware of His identity (Genesis 18:3). If the translation used William Tyndale's suggestion, the Hebrew Adonai was translated as "Lord" to distinguish it from YHWH. In the New Testament, "Lord" is the Greek kurios, which simply means master, whether referring to God (Matthew 1:20), Jesus (Matthew 7:21), or a general authority (Matthew 18:27).
GOD: "God" is an old English word which may have its origins in the Proto-Indo-European word ghu, which means to pour a libation. In the Bible, it is used for the Hebrew Elohim, which just means god, but since God is the only true god, it's an appropriate identifier. The prefix of Elohim, "el," is used in many proper names. Elohim is also related to the Arabic Allah. "God" in the New Testament is the Greek theos, which means any deity.
LORD GOD/Lord GOD: Combining the two gives us Adonai YHWH. Adonai is Hebrew for lord or master; its root word can also mean father. Adonai YHWH literally means "LORD Lord." Since that doesn't make much sense, it's usually translated "LORD GOD."
For more on the names of God, see our article on the names of God.
What are the names of God? What do the names of God mean?
What is the tetragrammaton? What does YHWH mean?
How should I understand God as Abba Father?
What is the Trinity?
Why should we study the Bible?
Truth about God