Madisyn Taylor for DailyOm had a nice write up on the differences between meditation and prayer. So many do not realize that they are not the same thing at all though there is no doubt that many Christian mystics (see that meditation is supportive of prayer though not directly mentioned in the Bible) as for them meditation is a “receptive” quality (see Spirit of Prayer on that)
Prayer is when we ask God for something or give thanks.
When we pray, we use language to express our innermost thoughts and feelings to a higher power. Sometimes, we plumb the depths within ourselves and allow whatever comes to the surface to flow out in our prayer. At other times, use formal prayers, poems, psalms, prayers written by another but that express what we want to say. Prayer is reaching out to the universe with questions, pleas for help, gratitude, and praise.
When we meditate, we cease movement and allow the activity of our minds and hearts to go on without us in a sense. Eventually, we fall into a deep silence, a place that underlies all the noise and fray of daily human existence. In this place, it becomes possible for us to hear the universe as it speaks for itself, responds to our questions, or sits with us in its silent way.
Both prayer and meditation are indispensable tools for navigating our relationship with the universe and with ourselves. They are also natural complements to one another, and one makes way for the other just as the crest of a wave gives way to its hollow