Yahweh, YHWH, and variants is usually “LORD.” (all caps)
“Lord” in the Old Testament is usually Adonai (and variants)
“Lord” in the New Testament is usually Kyrios (and variants)
There are exceptions.
Correct, but because Koine Greek was the predominate language of the world, the Hebrew scriptures were translated into Greek as the Septuagint. These scriptures were commonly quoted by Jews and Christians during the time the New Testament was being written. About half of the quotes of Old Testament scriptures in the New Testament use the Septuagint phraseology. About half re-translate from the original Hebrew to clarify their intended use and applicable meaning
Consider this quote by Paul, for example:
Romans 10:13
For “whoever calls on the name of the Lord shall be saved.”
This is from a prophecy in Joel 2:32. Peter also quotes this passage in Acts 2:21.
Joel uses the Hebrew name of God, Yahweh, but the LXX (Septuagint) Greek translates His name as kurios, i.e. Lord, just as Paul and Peter quote it. Note that both Paul and Peter are specifically using this Old Testament quote to refer to Jesus as THE Lord, i.e. Yahweh.
The message is: Whoever calls on the name of the Lord Jesus Christ, will be saved. Jesus is THE Lord (Yahweh).
Which is why I never use the word “God” when sharing my faith. I either use “the Lord God Almighty” or the “Lord Jesus Christ”, and that only after expressing the meaning of His Name.
“God” to a pagan could be the stone next to your foot....