Prajanananandaji: When you pray, it is you talking to God, while in meditation, it is God talking to you. In meditation you close your eyes to feel the presence of God within you. Love and meditation are inseparable. While praying you look at an image or any symbol, you sing the glory of God and you Talk to God, therefore you are using your senses, while meditation is a silent prayer; you close your eyes, your ears, your mouth to perceive the otherwise inaudible talk of God. When you pray you talk to God, while in meditation you listen to God talking to you. Those who meditate go into the inner chambers of silence and listen to the melodious sound OM or AMEN, the on-going primeval sound. Prayer is the expression of one’s love for God through senses while meditation is a silent prayer and the senses are introvert.
Source: Lineage of Kriya Yoga Masters by Paramhansa Prajanananda, pg 125-126