Angels according to the book of Hebrew 1:14 are ministering spirit assigned to help those who are heirs of salvation. Meanwhile, the saints are the holy prophets and apostles that prepared the way of salvation for us. The saint also can represent the godly people who are without the guilt of sin. 

Saint is a human position not a celestial office. Angel is a celestial being primarily meant to be in heaven, but the fall of Satan brought down some angels who are now demons. Angels were created spirits, according to Paul the apostle, they are ministering spirits. They are not made from the dust. They are of heaven and they are made of light. They are the stars of heaven. On the other hand, saints are earthly being, made to worship God on earth but sin brought death upon man and him would become like the angels when he dies.

Saint dies but angels don't die because they are spirits. Saints represents the church in heaven, angels represents God as in the case of the angel that came to meet Daniel in Daniel chapter 10. Also in Genesis chapter 18 and 19 angels came to meet Abraham and Lot.  In Luke 1:26-38, Angel Gabriel came to minister to Mary. 

Angels are the host or armies of Heaven, while saints are armies of salvation here on earth: they fight the good fight of faith (1 Timothy 6:12). According to Jesus in Matthew 13:39, the angels are the laborers of the harvest. They reap the harvest while the saints are the sower. Paul said "I plant and Apollos water." (1 Corinthians 3:6). The angels draws men to salvation. They converts people to Christ. The saints only sow.

The cherubim and Seraphim represent the glory of the Lord, both angels had six wings and stand at the right and left side of throne of  God. While the saints represents the glory of the church. Moses and Elijah are the two olive trees that stand at the right and at the left of Christ. They appeared to Jesus at the mount of transfiguration. 

"After six days Jesus took with him Peter, James and John the brother of James, and led them up a high mountain by themselves. There he was transfigured before them. His face shone like the sun, and his clothes became as white as the light. Just then there appeared before them Moses and Elijah, talking with Jesus." (Matthew 17:1-3).

Angels have wings, saints don't have. The saints spiritually are olive trees and the lampstands (Revelation 12:4), but the angels are the reapers and the 7 stars. 

"The enemy who sowed them is the devil, the harvest is the end of the age, and the reapers are the angels." (Matthew 13:39).