I'm currently reading The Nicene Creed by Phillip Cary
And I'm learning a lot, both of import and tangential. one of the big things is that when LORD (all caps) is written, it stands for the Tetragrammaton, the Wholy (or Holy) Unspeakable Name of God. When the word is Lord (only initial capital letter), it is a title... I think an honorific, although the relationship between the person speaking and that which is addressed as Lord isn't made clear. Reading Wikipedia, Adonai is translated as Lord... BTW, the Wikipedia entry on the 7 names of God is fascinating. I didn't know that Adonai and the name of the Greek god Adonis are linguistic cognates.
The Nicene Creed makes a distinction between Father and Lord. I understand the relationship implied by the word Father, it's the Creator and the created. I'm still not sure about the relationship implied by Lord.
Cary says he gets all his information from a book, Early Christian Creeds by Kelly. I'd love to read that larger work, but it's $80, and I can't afford it.