These are Guest and Administrator accounts.
Guest account is for users which do not have a permanent account on a PC but use it frequently.
Guest user can not modify anything permanently on the system.
Administrator account, on the other hand gives ultimate level of access to the user.
The administrator can perform various sensitive tasks which other accounts are not permitted to.
These two accounts are inactive by default.
you might activate them when you feel a need for their use.
The user account is an unelevated administrator account while the built-in administrator account an elevated one.
This account is unprotected initially.
It is highly recommended that you protect this account with a strong password.
(The entered password will not be shown as asterisks).
source: www.techworm.net
