" In a crossmedia environment, content is repurposed, diversified and spread across multiple devices to enhance, engage and reach as many users/viewers as possible. It is common to call crossmedia "content 360". It is generally the same program re-edited for different screens, fragmented content disseminated on different platforms, possibly incorporating extra content and channels to extend the viewers' experience. Brand here plays a key role and needs to be always identifiable. A typical form of crossmedia is when the plot of the story ends with a call-to-action, and drives the audience across different media. A good example is the BBC's Spooks, where, at the end of the TV episode, a cheerful announcement gives directions to a website.
In transmedia storytelling, content becomes invasive and permeates fully the audience's lifestyle. Stephen Erin Dinehart, who coined the term transmedia and created the VUP (viewer/user/player) relates this model to Richard Wagner and his concept of "total artwork" ("Gesamtkunstwerk") where the spectator becomes actor/player. A transmedia project develops storytelling across multiple forms of media in order to have different "entry points" in the story; entry-points with a unique and independent lifespan but with a definite role in the big narrative scheme.
More concretely, from the originator's perspective, transmedia is content embedded with marketing strategies, where content is treated as “goods” to be franchised. Each franchise should have the goal of expanding the audience experience and drive for more consumption in the overall scheme.
Both crossmedia and transmedia are obviously multimedia approaches, using largely of any available channel, tool and media to tell a story. The difference between the two is to ascribe to a consequent evolution in public demand. Content spread across various media (crossmedia) is no longer satisfying enough, viewers wants more, they are becoming VUPs and in viewing/using/playing want to participate, and to a certain extent create, the story themselves." (http://www.lunchoverip.com/2008/05/from-crossmedia.html)
"The most self-explanatory example of multi/Xmedia/transmedia production is a recent participatory drama by Swedish public television SVT, Marika which won the 2008 iEmmy Awards. Marika included a TV drama series, in-studio debates, online virtual environments, events across Sweden, blogs (picture), chats, fabricated documents and props, forums and mobile games -- and drew the public, and the other mainstream media, into the story. Following the iEmmy Awards win, Marika is creating some turmoil among public broadcasters, but it is also pushing content creators to start daring on innovative productions." (http://www.lunchoverip.com/2008/05/from-crossmedia.html)