What is the difference between a mixture and a pure substance

A mixture is broken down substances make up of multiple elements which can be original traces of substances while a pure substance can only one element constant throughout the entire substance. It is a pure element.

A mixture is a substance that has been mixed together with something else, whereas a pure substance is just made with a single element. For example, diluted orange juice has a mixture of Orange juice and water; pure orange juice isn't diluted with any water.