بِسْمِ اللهِ الرَّحْمٰنِ الرَّحِيْم
The word Ar-Rahmaan indicate that Allah’s comprehensive mercy which He shows to all Hi creation without exception; that He creating them and providing for them. The word occured 57 times in The Qur’an.
The word Ar-Raheem indicate the particular mercy that He has exclusively for the believers, both in this life and in the hereafter. The word occured 123 times in The Qur’an.
In Surat Al-Fatihah (1:1) we can find both words appeared in the same phrase, “In the name of Allah The Most Gracious The Most Merciful.”