What is the different between Epistles and Gospels?

Like radiant said a gospel means good news so you can look at a gospel as a news report. An epistle is a letter and is either addressed to a person or persons as well as it can be titled with the person's name and left for others to read like a diary.

The Gospels and Epistles were written in the New Testament, what were the types of books written in the Old Testament?

We are all Joint-Heirs with Christ

An epistle is a writing or letter addressed to a group of people or a person. In the new testament epistles were letters written by various apostles to the christian churches scattered all over the Roman empire. As was noted some apostles also wrote gospels. The word gospel means Good News and were written on the life and teachings of Christ who came to bring Good News to the world, hence the title gospel according to....These books gave accounts of events which took place in the life of Jesus while he was here on earth from the perspective of different disciples that followed him while he was here among us.