What characteristics and beliefs of the three religions make them different?

It really depends on what three religions you're talking about. I'll cover the five main ones just to be sure.

Hinduism- They believe in many gods, many of which are animals. Each god is assigned to different aspects of life.

Buddhism- They don't have a "god", persay, just a leader. They're the main religion with the belief in karma.

Judaism- They believe that Jesus was a prophet rather than the son of God. They also believe that the son of God is yet to come.

Christianity- They believe that Jesus was the son of God and will one day come again to save us.

Islam- Have a holy book called the Qu'ran, and they have a lot of the same basic beliefs as Christianity and Judaism. There are five pillars in this religion.