The general meaning of whistleblower is someone or an informant who exposes wrong doing within an organization. When we say informant, this is a person who gives information about something whether it is bad or good... So a whistleblower is still an informant who only discloses negative information...

A whistleblower notifies authorities of wrongdoing and/or illegal activities by their employer or associates. The notification is through official channels. The name of the whistleblower is known publicly - at least once they have made the information official. An informant also tells authorities of wrongdoing by an employer. However, the informant's name is usually secret, being revealed only at the trial of the wrongdoer. The whistleblower is probably in danger of losing his job. The informant often risks retaliation in the form of bodily harm. Strictly speaking, a whistleblower is also an informant, because he or she informs somebody. When the words are used in news stories, however, "informant" usually gives a picture of something secretive.

Yes, a specific kind of informant expossing wrongdoing within a certain organization with the good aim of stopping it !