QUESTION:: Is there any difference between an web address with "www" and without one?
ANSWER::: there is no difference unless you specify this in your DNS
ie www can have an A record which points to a different IP address.
You can think of the www as being a type of alias for the domain name or otherwise where the web portion of the domain name lives.
Never argue with an idiot; First he takes you down to his level and then he beats you with experience.