The angel Gabriel said, "Hail, full of grace, the Lord is with you" (Luke 1:28). The phrase "full of grace" is a translation of the Greek word kecharitomene. This word represents the proper name of the person being addressed by the angel, and it therefore expresses a characteristic quality of Mary.
The grace given to Mary is at once permanent and of a unique kind. Kecharitomene is a perfect passive participle of charitoo, meaning "to fill or endow with grace." Since this term is in the perfect tense, it indicates a perfection of grace that is both intensive and extensive. So, the grace Mary enjoyed was not a result of the angel’s visit, and was only as "full" or strong or complete as possible at any given time, but it extended over the whole of her life, from conception onward. She was in a state of sanctifying grace from the first moment of her existence to have been called "full of grace."
Mary is NOT equal to God, nor do catholics suggest she should be viewed as such.
In the beginning, God created Adam, Eve, and the angels without sin, but none were equal to God. Most of the angels never sinned, and all souls in heaven are without sin. This does not detract from the glory of God, but manifests it by the work he has done in sanctifying his creation. Sinning does not make one human. On the contrary, it is when man is without sin that he is most fully what God intends him to be.