Salah is formal prayer said in Arabic and following a set structure. Du’a is personal prayer which may be used anytime and is from the heart.

The congregational prayer, Salat al-Eid, was performed in the morning ... Mallam Baba Al-hassan, Deputy Chief Imam of the Ahlussuna Wal-Jama’Ah, delivered a sermon, Khutbah, after the prayer ...

is the word used to refer to personal prayer that is done in addition to Salah. This may take the form of quietly talking to God in one’s head, reciting set prayers or asking Allah for help.