Prayer (oratio) is the personal response to the chosen text of Scripture that was used for meditation. With the help of grace, thoughts move to prayer. This is the response of the heart to ask for the grace that corresponds to the text or perhaps just to draw closer in union with God. Prayer is conversation that asks with love and with the intention to grow in the virtues. In this affective element of lectio the soul desires God.
Contemplation (comtemplatio) is the final element of lectio. It is a loving gaze at length where sometimes, by the grace of God, infused contemplation occurs and the soul is raised above meditation to experiencing the mystery and reality of the Scripture text. The experience is one of peace, harmony and quiet. God's presence is experienced as a loving awareness where His love is felt and lovingly returned.
In summary, reading seeks; meditation finds meaning; prayer demands; contemplation tastes God.
For a more excellent explanation on lectio divina check out the following link where in a ten minute video Dr. Tim Gray expounds on this ancient practice.