There is indeed a difference between mass media and mass communication, but indeed it’s a very complex question as both are interlinked. In the simplest academic terms, Mass communication refers to the act of disseminating information to the mass/public, whereas mass media refers to the medium/method employed to disseminate this information. For example, broadcasting is a form of mass communication which is basically taught in the bachelor in mass communication.
News is broadcast via various mass media such as television channels or radio channels or a certain film. Thus, One cannot exist without the other!
However, in every day use, both terms are used interchangeably. Media is often loosely used to refer to the press, even though it encompasses entertainment media as well as news media. Books, newspapers, magazines, television, cinema/film, and the internet are all forms of mass communication, and each particular book, or a particular channel, or a particular website would be the mass media.
What the professionals do with the media channel they are a part of, to reach out to their audiences, is engaged in mass communication. It is also for this reason that the study of the mass media is usually referred to as the study of mass communication. For this the applicants have to get enrolled in courses in mass communication