Difference between Repentance and Forgiveness in Islam

Istighfar (seeking forgiveness) is of two types, depending on whether the word is used alone or is accompanied by the word Tawbah (forgiveness). When it is mentioned alone, it essentially means the same as Tawbah.

The two words are interchangeable, each carrying the meaning of the other, when mentioned separately.

When the two words are used together, Istighfar means seeking protection from the evil of what is past, and Tawbah means returning to Allah and seeking protection from the evil of one’s own bad deeds which one fears may lie ahead in the future.

Istighfar and Tawbah are among the pairs of words which the scholars say convey one another’s meanings when used alone, but which have their own separate meanings when they are used together.

For more details, please see the following answers:

Does Allah Forgive All Sins?

How to Repent in Islam

Conditions of Repentance

Will Allah Forgive Me If I Repeat the Same Sin?

Acceptance of Repentance

Seeking Forgiveness is a Means of Strengthening the Body

And Allah knows best.