Is Fajr prayer the same as Subh prayer, and when exactly does it begin, and does the first Adhan mean no prayer and only Suhoor, and when is the second Adhan called in the United Arab Emirates?

Fajr prayer is the Subh prayer, and its time begins from the appearance of true dawn and extends until sunrise. If the call to prayer (adhan) for Subh is given, no voluntary (nafilah) prayers should be performed except for the two rak'ahs of Fajr. Exceptions to this include voluntary prayers that have a specific reason, such as the two rak'ahs of circumambulation (tawaf) and greeting the mosque (tahiyyat al-masjid), as well as the voluntary prayer for someone who overslept.