What is the difference between fan-writing and music journalism?

Ultimately there are huge similarities between fan-writing and music journalism. They're both writing about something they have passion for and generally both have an in depth knowledge of writing. However the criticism of the music journalism is lost amongst the fan-writing, there's a vague understanding of analysing the music, more opinion than actual substance.  

"Professional music journalists are seen as people who write because they are paid to do so, not because they have any particular interest in what they are writing about." Fan-writing tends to be more focused in a positive way, and with the lack of professional wring techniques but ultimately gets the same point across, just from a different aspect.

BIBLIOGRAPHY

http://www.lundwood.u-net.com/fandissy/fdhist.html