Are Login and Username the same or different?

User name is the name the computer gives you when itasks you for owner's name details during installation ie: for Simon Shera it would be simon, unless set as simon12 (or similar) by user. The password is the one you set. Say XIMw@88&. Best to include upper and lower case letters, figures and characters in this. On some systems password causes problems if longerr than eight characters. In that case, computer will also ask you if you require it to be truncated. If this is so, automatic truncate will cut password back to first eight characters.

I will reword question, to clarify. If I Ctrl+Alt+F2 (any F1 to F6) it brings up a page, asking for Login and Password. What do I put for Login? Username will not work. It says Login is not correct. Both my username and password have eight characters, but not the same. I was made aware of problem at https://answers.launchpad.net/ubuntu/+source/software-center/+question/205107, so others have same problem. I have tried all four Ubuntu releases I have many times, am sure i put in correct username and password.

A bit about the terminology:
A "login" (also "log in" and "log-in"), is the process of authentication to a computer system.
For this you need your "login user name" and the matching "password". There are also other ways to authenticate, but this is the most common way. Since computer scientists are efficiant people, they like to shorten things. And so they use several short forms for "login user name": "login", "login name", "user name" or "user". All this means the same in the context of a login prompts.

Listing /home will not give you the list of users. Every user can have an other home folder than /home/username.
See the root user for example, it's home folder is /root. You can get a list of user with the command "getent passwd". It will list some additional data, like home folder and user id (which is a number and different from the login user name).

To get your own user name, you can use "whoami" or "id" (which will give additional group info).
Also "id joe" will give the same info about the user "joe".

To change a users password, which is also important to log in, you can use
sudo passwd joe
It will first ask for your personal password (not joe's) and then a new on for joe. Read the messages carefully. Also note that your typing will not be shown on the screen (no ****).

Thanks Patrick and Thomas. Your answers have confirmed the way I though it worked.