What is the difference between a mixture, a solution, and a pure substance?

A mixture is a compound of two or more substances a pure substance is only made of one kind of atom and a solution is composed of a liquid substance made of two or more types of atoms

A mixture is a material made up of two or more different Chemical substance/substances which are not chemically combined, a solution is a homogenous mixture of two or more substances in relative amounts that can be varied continuously up to what is called the limit of solubility, and a pure substance is a substance that has a fixed chemical composition

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab.