Yes and no. I see what you are saying, but in my opinion every site can have its own definition of user and visitor. For some sites the terms may be interchangeable, while for other sites they have completely different meanings.
Let's take HN for example (I don't know if HN considers this their metric or what, just using it as an example.). Let's say they made a change that now requires everyone to login to the site each time they visit. So if you closed your browser window or were inactive for a period of time you would have to log back in. While you could still read posts and comments, you would be unable to submit new stories or comment until you logged in. While you are not logged in you would be considered a visitor. But when you log in, you now become a user.
While at first the traffic, or visitors, may remain the same, without participating users on the site the number of visitors will eventually drop as not as many people are submitting or commenting.
A site that does not require interaction, may on the other hand, simply use the two terms (visitor & user) interchangeably.
Let's take HN for example (I don't know if HN considers this their metric or what, just using it as an example.). Let's say they made a change that now requires everyone to login to the site each time they visit. So if you closed your browser window or were inactive for a period of time you would have to log back in. While you could still read posts and comments, you would be unable to submit new stories or comment until you logged in. While you are not logged in you would be considered a visitor. But when you log in, you now become a user.
While at first the traffic, or visitors, may remain the same, without participating users on the site the number of visitors will eventually drop as not as many people are submitting or commenting.
A site that does not require interaction, may on the other hand, simply use the two terms (visitor & user) interchangeably.