The definition that appears behind Citizen Journalism is the involvement of non-professionals in reporting news.   The idea behind citizen journalism is that people without professional journalism training can use the tools of modern technology and the global distribution of the Internet to create, augment or fact-check media on their own.  This is according to http://dictionary.reference.com/browse/citizen+journalism Examples include things such as blogging.

Participatory Journalism has been considered to be the same definition.  I think, however, that participatory journalism is when the audience partakes in commenting and giving opinion on the news that is being delivered.  It is also when viewers send what they think is news worthy to those that are professionals so that they can present the news such as pictures, video, etc.