Almost no one noticed, however, even though Microsoft’s policy changes are much the same as those that Google made to its privacy rules this year.

Google’s expanded powers drew scathing criticism from privacy advocates, probing inquiries from regulators and broadside attacks from rivals. Those included Microsoft, which bought full-page newspaper ads telling Google users that Google did not care about their privacy, an accusation it quickly denied.

The difference in the two events illustrates the confusion surrounding Internet consumer privacy. No single authority oversees the collection of personal information from Web users by Internet companies. Though most companies have written privacy policies, they are often stated in such broad, ambiguous language that they seem to allow virtually any use of customers’ personal information.