A refugee is a person, who is forced to leave their home. They can be forced by natural disasters, war, religious disagreements and much more.
When you migrate, you are known as an immigrant. There are two different types of immigrant, national and international. National is when they move out of the country however international is when they move but stay in the same country. Just because they migrated doesn't necessarily mean you are a refugee. If the reason to as why you are moving is not forced you are just an immigrant.
There are many different reasons to migrate and here are some of them:
push factors are the things that force you to move. These can be no jobs or not enough money.
pull factors are the thing that make you want to migrate. This could be good jobs and homes.