Power

I am a strong believer in the power of prayer. Prayer performed properly can help you whether you are a christian or not. However, there is something I believe that even rivals the power of prayer. That is the power of the priesthood. So what is the difference?  Let us study, first, what each of these are.

Prayer
"A reverent communication with God during which a person gives thanks and asks for blessings. Prayers are addressed to our Heavenly Father in the name of Jesus Christ. Prayers can be either spoken aloud or silent. A person’s thoughts may also be a prayer if they are directed to God. A song of the righteous may be a prayer to God (D&C 25:12).
The object of prayer is not to change the will of God, but to secure for ourselves and for others blessings that God is already willing to grant, but that we must ask for in order to obtain.
We pray to the Father in Christ’s name (John 14:13–14; 16:23–24). We are truly able to pray in Christ’s name when our wishes are the wishes of Christ (John 15:7; D&C 46:30). We then ask for things that are right and thus possible for God to grant (3 Ne. 18:20). Some prayers remain unanswered because they in no way represent Christ’s desire but spring instead out of the selfishness of man (James 4:3; D&C 46:9). Indeed, if we ask God for unrighteous things, it will turn to our condemnation (D&C 88:65)."

Priesthood
"The priesthood is the authority to act in God’s name. The same priesthood authority that existed in the original Church established by Jesus Christ exists in The Church of Jesus Christ of Latter-day Saints today. The Church is directed and led through this authority.
All male members of the Church who are prepared receive the priesthood in order to help lead the Church and serve Heavenly Father’s children. A man with the priesthood might serve in some of the following ways:
Leading congregations of the Church
Performing the ordinances of the Church, such as baptism
Blessing those who are sick
God expects those who hold this sacred priesthood authority to follow the example of Jesus Christ and serve with love, gentleness, and kindness."

Here is a good example of the power of the priesthood in action. I testify that the power of God is granted to man to act in His name by His will only l, and anyone who tries to use it otherwise will not have it. I have personally felt and witnessed such sacred power.
Sancitfy yourselves