A business that is incorporated does have limited liability - limited only to the assets of the company.
There are other types of limited liability entities, including LLC's which provide other types of limited liability.
The suffix Inc, or LLC or PA/PC explain the type of entity and by reference the type of liability it holds. Check the Secretary of State's Office in your state for more information.
Unlimited is not an official entity type, and really is just part of the name of the company.
I think in other countries, Ltd is used to denote a similar limited liability entity type.
Denae