Guests - A guest account allows people to have temporary access to your computer. People using the guest account can't install software, hardware, or change settings. While the default "Guest" account cannot be password protected, an existing user account made into only a guest account using an option below can have a password.
Standard user (Users) - The standard account can help protect your computer by preventing users from making changes that affect the system or other users. If a standard user wants to do something that affects the system or other users, they will get a
UAC prompt to provide the administrator's password before being allowed to do so. If UAC is not turned on, then the standard user will not be allowed to do so.
Administrators - Administrators have complete access to the computer and can make any desired changes. To help make the computer more secure, administrators may get a
UAC prompt, if UAC is turned on, to provide their password or confirmation before being allowed to make changes that affect the system or other users.