Reportage is a French term, that means the same as "report". For example instead of,
The reporter writes reports for his newspaper.
You would have,
The writer writes reportage for his newspaper.
However, in England and America I have found that editors have a different meaning for the term reportage. They often consider "narrative" reports -- long stories you find in the Sunday section of the newspaper or in magazines like Vanity Fair or The New Yorker -- reportage because it generally is better written and more elaborate. In contrast these editors consider something off the AP Newswire (which are brief concise, "just the facts" stories) to be a "report".