What is the difference between LORD and GOD?

Building on what Ray Butterworth has described as the convention in translating Hebrew to English, here are 4 good examples highlighting the difference between usage #1, #4, #5, #6. I provide the original Hebrew text courtesy of the Logos Bible Software's Hebrew-English Interlinear Bible. Notice how the original Hebrew word yhwh is translated to English as LORD (all caps), and the Hebrew word elohim as God. (Note: Hebrew language uses right-to-left convention, like Arabic until today). I use ESV as the English translation.

I find it very useful to simply think of LORD all caps as denoting Israel's God's personal name (like Trump) while God as denoting his office (like President). Sometimes we refer to Trump as Mr. Trump (personal name), Mr. President (Trump's office), a president (doesn't matter whether it's Trump or not), or President Trump (Office and occupant's personal name combined). So depending on the story's need, the story uses a different construct for a different emphasis:

1. The personal name of the god: when you need to distinguish one God over the other, esp. in polytheistic society like in the time of Moses, as in Ex 6:2-3. In the same verse, God also informed Moses that when He revealed Himself to Abraham He used a different personal name "El Shaddai" (translated as "God Almighty" in ESV, compare with the Hebrew text):

   God spoke to Moses and said to him, “I am the LORD. I appeared to Abraham, to Isaac, and to Jacob, as God Almighty, but by my name the LORD I did not make myself known to them.

   

2. A particular people's god: to emphasize the difference between one nation's God with another's, as in how Pharaoh said "your God" in Ex 8:28 (Ex 8:24 in Hebrew Bible's numbering):

   So Pharaoh said, “I will let you go to sacrifice to the LORD your God in the wilderness; only you must not go very far away. Plead for me.”

   

3. A generic god: to emphasize the function of the being, as how God helped Moses to appear like a god to Pharaoh, as in Ex 7:1:

   And the LORD said to Moses, “See, I have made you like God to Pharaoh, and your brother Aaron shall be your prophet.

   

4. The god's personal name plus office together: see how at the end of Ex 9:29-30 Moses added the office (elohim) of Israel's God's personal name (yhwh), for emphasis.

   Moses said to him, “As soon as I have gone out of the city, I will stretch out my hands to the LORD. The thunder will cease, and there will be no more hail, so that you may know that the earth is the LORD’s. But as for you and your servants, I know that you do not yet fear the LORD God.”

   

In the Old Testament, Exodus 20:2, in the part with the 10 commandments, God says to Moses "I AM the Lord your God". And a textural explanation for why this is the case is:

The conventional "the LORD" in English translations renders יהוה in the Hebrew text (transliterated "YHWH"), the proper name of the God of Israel, reconstructed as Yahweh. The translation "God" renders אֱלֹהִים (transliterated "Elohim"), the normal biblical Hebrew word for "god, deity".

Basically, if you see the all capital letters "LORD" in the Bible, that's a stand-in for the Holy Name of God. So that's like saying "Hi, I'm Peter a lazy mod on Christianity Stackexchange, you shall have many mods before me."

In the New Testament, the word Lord (as used by Jesus and St. Peter)

You hail me as the Master, and the Lord; and you are right, it is what I am.

ὑμεῖς φωνεῖτέ με: ὁ διδάσκαλος καὶ ὁ κύριος, καὶ καλῶς λέγετε: εἰμὶ γάρ.

Vos vocatis me Magister et Domine, et bene dicitis: sum etenim.

John 13:13 - New Advent

Is the title Lord, like Lord of the manor or King of the country.

Kyrios or kurios (Ancient Greek: κύριος, romanized: kýrios) is a Greek word which is usually translated as "lord" "master" or "teacher". In religious usage, it is sometimes translated as God. It is used in the Septuagint translation of the Hebrew Bible and the Greek New Testament. Kyrios appears about 740 times in the New Testament, usually referring to Jesus.

So there's actually 3 words to worry about, two in Hebrew an one in Greek. But they're not talking about different gods, according to the Trinitarian belief (i.e. almost all Christian faith traditions). But the Greek Lord (kyrios) is a Title for Jesus (the second person of the Trinity) and Hebrew LORD is the personal name of God (which I think is referring to the first person of the Trinity, but I'm not certain of this)

The all upper-case "LORD" and "GOD" are used where the original Hebrew used the sacred name of god, YHWH (יהוה).

Traditionally, that four letter name (Tetragrammaton) is not supposed to be pronounced except by the high priests on the Day of Atonement.

To avoid accidentally saying it while reading the Hebrew scriptures, incorrect vowel marks are added to the word, specifically the vowels from "Adonai", meaning "lord". Anyone reading it would know to say "Lord" at that point.

This article, "Why Does the Old Testament Sometimes Capitalize Lord or God?", includes a summary of the general rules that apply:

1. When you see LORD, the specific name YHWH is used and it always refers to Him.

2. When you see lord, the word adonai is used in such a way as to refer to a human master or lord.

3. When you see Lord, the word adonai is used to refer to the true God.

4. When you see God, the Hebrew words elohim, el, or eloah are used to refer to the one true God.

5. When you see god or gods, the Hebrew words elohim, el, or eloah are used to refer to idols, spiritual beings, the objects of other nations’ worship, etc.

6. When you see Lord GOD, the author has used both adonai and YHWH together.

So, to answer the original question, there is no real difference between "LORD" and "GOD":

• "LORD" means that "YHWH" is supposed to be said as "lord".
• "Lord GOD" means that "YHWH" is supposed to be said as "god" (otherwise the first rule would suggest saying "lord lord").