Sheikh `Abd Allah b. Sardâr , lecturer at the `Umawî Mosque in Madinah
The manner of performing prayer is same whether the prayer is performed silently or out loud. There are, however, some differences. The most important of these is that in an audible prayer, when the imam recites a verse that necessitates he makes a prostration, he should prostrate and the congregation must do the same, whereas in the case of silent prayers, scholars dislike it for the imam to recite such verses because of the confusion that the extra prostrations will cause for the congregation.
Some other very minor differences of a similar nature also exist.
Source: Islam Today