Do check out he background before starting to avoid confusion

First sphere:

Seraphim

 The highest order of the choir of angels. 

Cherubim

Ranks after the seraphim and are the second highest in the nine hierarchies or choirs of angels. 

Thrones

The lower Choir of Angels need the Thrones to access God.

Second sphere:

Dominions

Dominions are Angels of Leadership. They regulate the duties of the angels.

Virtues

Virtues are known as the Spirits of Motion and control the elements. They govern all nature, control seasons, stars, moon and even the sun. They are also in charge of miracles and provide courage, grace, and valour.

Powers

Powers are Warrior Angels against evil defending the cosmos and humans. They fight against evil spirits who attempt to wreak chaos through human beings. 

Third sphere:

Principalities

Archangels

Angels

Credits to the different sources:

http://angels-angelology.com/hierarchy-and-orders

http://www.catholic.org/saints/angels/angelchoir.php