- Names and Attributes of Allaah - The difference between al-Rahmaan and al-Raheem.

What is the difference between al-Rahmaan and al-Raheem?.
Praise be to Allaah.
Al-Rahmaan and al-Raheem are two of the names of Allaah which refer to
Allaah's attribute of Mercy.
Al-Rahmaan refers to thevastness of Allaah's mercy, and al-Raheem
refers to its effect on His creation. So al-Rahmaan is the Owner of
vast Mercy, and al-Raheem is the Owner of Mercy that encompasses His
creation.
Shaykh Ibn 'Uthaymeen (may Allaah have mercy on him) said: "Al-Rahmaan
is the Owner of vast mercy, because the fa'laan formin Arabic
indicates vastness and abundance,as it is said rajal ghadbaan (a very
angry man) when he is filled with anger.
Al-Raheem is a name which refers to the action, as the fa'eel
formrefers to the doer of an action. So the phrase al-Rahmaan
al-Raheem indicates that the mercy of Allaah is vast, as is understood
from the name al-Rahmaan, and that it encompasses His creation, as is
understood from the name al-Raheem. This is what some of them meant
when they said that al-Rahmaan refers to mercy in a general sense and
al-Raheem refers to mercy that is specifically for the believers. But
what we have mentioned is more accurate."
From Sharh al-'Aqeedah al-Waasitiyyah, 1/22
And Allaah knows best.