What is the difference between alias and nickname?

Answer 1

A nickname is an addition to or a substitute name for someone. For example, Jim may be called Jim Bob by family and friends or someone who was called peanut when they were small may go through life being called Peanut by those familiar with them.

An alias is another name. It is a false or assumed identity. For instance, Jonathan Meeks may assume a derivation of his name, John Meece, or even a totally different name, something like Charles Smith.