What is the difference between username and nickname?

There are some differences between usernames and nicknames, and their function in Khan Academy:

1. Username

• You are able to use your username to log into Khan Academy, just as you can also log in using your email.
  

Nickname

• This is how your name will appear around Khan Academy, and how your coaches and the Khan Academy community will recognize you.
• You cannot use your nickname to log into Khan Academy.

You can learn how to update your username and nickname here.