In system settings 'username' displays the 'full name you enter when creating the account. By default the 'account' name, which is the name for the home folder, just removes spaces from the 'full name'.
Does it matter if these are completely different?
No, it doesn’t matter at all. is also known as the short username.
I always set up my accounts with my full name, and change the short username to something completely different.
Just don't use any spaces or special characters in the short user name as it is best to stick with just alphanumeric characters. A hyphen or underscore character is fine (just not the first character), but most others should be avoided just to be safe.
Is 'username' the 'full name' or 'account name', and should they match?
