Difference between iqama and adhan

As Salamu Alaikum Wa Rahmatullahi Wa Barakatuh

In the name of Allah, We praise Him, seek His help and ask for His forgiveness. Whoever Allah guides none can misguide, and whoever He allows to fall astray, none can guide them aright. We bear witness that there is none worthy of worship but Allah Alone, and we bear witness that Muhammad (saws) is His slave-servant and the seal of His Messengers.

Sahih Al-Bukhari Hadith 1.579         Narrated by Anas ibn Malik

Bilal was ordered by the Prophet (saws) to repeat the wording of the ‘Adhaan’ for prayers twice, and to pronounce the wording of the ‘Iqama’ once except "Qad-qamat-is-Salat".

Although the wordings of the ‘adhaan’ and the ‘iqama’ are quite similar, there is a distinct difference in their declaration.  The Messenger of Allah (saws) ordered Hadrat Bilaal (r.a.) to repeat the phrases of the ‘adhaan’ twice and in a slow-paced rhythm; and the declare the phrases of the ‘iqama’ only once in a faster-paced rhythm.

The main reason and wisdom behind the repetition of the phrases of the ‘adhaan’ twice and in a slow-paced rhythm is to make aware to the believers that the time of offering the prayer has begun, and the wisdom behind the declaration of the ‘iqama’ is only to signal to the believers present that the prayer is about to start and they should thus stand themselves in rows and make themselves available for congregational prayer.  

Whatever written of Truth and benefit is only due to Allah’s Assistance and Guidance, and whatever of error is of me alone.  Allah Alone Knows Best and He is the Only Source of Strength.