The word "angel" in Hebrew is malak and it carries the meaning: to dispatch as a deputy, a messenger, spec. of God a prophet, priest, teacher. Ambassador, angel, king, messenger (Strong's 4397). Hebrew has no "capital letters as does English, but we sometimes see Angel or angel in the English translation written that way by the translators to signify a difference. Reference to an angel usually means one of the many angels God created to be His messengers (Psalm 148:1-5). There are times when the reference carries a far greater meaning. We read "Angel of the Lord" in a number of scriptures and it is obvious that God is involved from the content of the rest of the passage. There are occasions when God appeared as an angel during some encounters with humans. Abraham saw three "men" approaching when he lived on the plains of Mamre. He recognized one as the Lord, but all three were referred to as men and later angels (Gen. 18:2,16, 19:1). Clearly the Lord and angels can appear in human form and eat and talk with humans. The word "Lord" appears thousands of times in the Bible from the Hebrew word YHWH (Strong's 3068). It has been translated to Lord because nobody knows the exact spelling or pronunciation of God's name in Hebrew and rather than be in error, Jews do not try to write or speak God's name. In the New Testament Greek the word "kurios" was used (Strong's 2962). It means supreme in authority and it is translated as Lord. In Scripture capitals are used to denote supremacy. Angel versus angel and Lord versus lord. Lord that is capitalized refers to the deity as in "Jesus our Lord." In some passages the word angel seems to indicate a deity, and may mean more than a created spiritual angel.
God has spoken directly to humans at times. Earlier we referred to Abraham and Moses was another one with whom God spoke face to face (Exod. 33:11), and Adam And Eve as well. God and the angels appeared to men in a way that was acceptable to the human eye and ear. There were times when God did not appear as a figure, but in a cloud or fire (Ex. 19:9). The term "angel of the Lord" is how translators have written the times when an actual angel that God had created was doing acting for God (Matt. 2:13, 28:2). Two of the three "men" who visited Abraham were created angels, the third was the Lord. Abraham knew the difference, though the three looked alike. He spoke directly to that "man" as my Lord. There is no doubt that God interacted with mankind many times and in different ways. His presence had to be controlled lest people be destroyed, so at times God appeared in pillars of fire and cloud, spoke with a voice that shook mountains or whispered in a gentle wind as He did to Elijah. It is interesting that Hagar had an encounter with the "Angel of the Lord" when she was fleeing from Sarah's anger (Gen. 16:7-13). The Angel said "I will multiply your descendants" and Hagar called the name of the Lord who spoke to her "You-Are the God-who-Sees". It is interesting to note the second time that Hagar had to leave was after Isaac was born. In this account, we read that the angel (small 'a') of God called to her out of heaven and the angel said "what ails you, Hagar?" and "I will make him a great nation" (Gen. 21:17-20). When we remember that the word angel can mean a lot of things including messenger of God, king and so on, we can see that at times what we are reading are the times in which the God of the Old Testament who we know of as the Logos and Word that later became Christ, was interacting directly with humans. Translators chose to use upper or lower case as they thought the meaning of the passage indicated. Jesus later said that nobody had ever heard the voice of God the Father, so clearly when a person heard the voice of God, it was not God the Father (John 5:37). Jesus said He did the will of the Father (John 6:38). It is not easy for our physical minds to understand that God is One.
Jesus stated that He did nothing without the will of the Father and that would mean that He is also a messenger or special envoy of the Father (John 5:19,27,30). There were times when the Bible recorded the "Angel of the Lord" speaking as though it was the Lord speaking and thus we can grasp the reason for using Angel at times versus angel. There is never a time when God the Father is not involved in all that happens. In the amazing drama that took place when God asked Abraham to sacrifice his son, it was the Angel of the Lord that called to Abraham. The words are interesting in this verse. The Angel of the Lord called to him from heaven and said: "Do not lay your hand on the lad, or do anything to him for now I know that you fear God since you have not withheld your son, your only son, from Me" (Gen. 22:12). The Angel of the Lord called a second time and said: "By Myself I have sworn, says the Lord, because ….". So, we see the Angel speaking as God. It was the Angel of the Lord that came up from Gilgal and said: "I have led you up from Egypt and brought you to the land of which I swore to your fathers and I said, 'I will never break My covenant with you'" (Judges 2:1). In the account of Manoah and his wife, the Angel of the Lord interacted with them and their conclusion was that they had seen God (Judges 13:22).
Hundreds of years later in the history of Israel, when the temple had been destroyed and was now being rebuilt, we see an angel speaking with Zacharias. This conversation seems to be between an angel who was acting for God and Zacharias, but the angel kept referring to the Lord (Zech. 1:9-19). Here we see this angel is not acting on its own, but stated that the Lord said. That is different that the angel speaking in terms of "I". When we read further in Zech. 3:1-10 that the Angel speaks seemingly on its own authority, this Angel stated that he had cleansed Joshua and at the same time made statements as: "Thus says the Lord of hosts" (verse 7). It can get to be confusing if we try to establish a standard that will always fit. The actions taken and the words spoken at times were such that those who saw this Angel feared for their lives because they thought they had "seen the Lord" and it appears that God did appear among men as an angel. Of course, we cannot be certain about the true appearance of angels. Ezekiel tried to describe four "living creatures" which had 4 faces, wings, hands and yet the likeness of a man (Ezek. 1). Trying to visualize something like this shows us that the angels that did come to work with mankind had to be acceptable to our minds. The Bible tells us there are cherubim, seraphim, powerful angels and more. We humans were created less or under the angels (Psalm 8:5). One really powerful angel became Satan who is described as a great, fiery, red dragon with seven heads, ten horns and ten diadems on his heads (Rev. 12:3).
One of the most confusing and yet wonderful chapters of the Bible explains that in the beginning was the Word, and the Word was with God, was God" (John 1:1).We are told that all things were made through Him and He was in the world, but the world did not know Him (verse 10). Jesus made it clear that He existed before Abraham (John 8:58) and since He said no one had seen or heard God the Father before He declared Him to the world, it was the Logos or Word that was known as God by Israel. Not only was He active, but the constant close work with God the Father never ceased. That also had to be true before He became flesh and walked the earth. The term Angel of the Lord, the Lord and God are interchangeable at times. The attempt to make the understanding clearer is why the Angel of the Lord was given a capital A.