Publishers permit different rights for different versions of your article.
Below are a list of commonly-used terms and explanations.
Image credit: © Jessica Lange. Licensed under Creative Commons CC BY 4.0 International
An assignment is the transfer of some or all of your rights to another party (e.g. a publisher). This assignment can last for the entire term of the copyright or for a specified period of time.
You may see the terms copyright transfer agreement or copyright assignment agreement. These mean the same thing.
A license gives another party permission to use your work under certain conditions, but you keep ownership of your copyright and the related rights. This can also work in the reverse; in many publishing agreements, you will transfer copyright to the publisher but the publisher will license certain rights back to you.
There are two main types of licenses: