For most people, a dio is :
1. A story told w/ pictures. It will usually contains text boxes and word balloons. It can have special fx added, be fotoshop'd, or many other things. Some amount of effort and time has been put in to create the visual story.
A dio tends NOT to be :
1. A picture set up in 30 seconds, shot and posted w/ no thoughts.
2. The dialogue taking place are set up on a different page. ie; you get picture and then a lengthy script.
3. Pictures of your collection.
4. Random pictures from a big 'diorama' one sets up. Usually has too many angles of the same shot and has NO story being told.
5. Pictures of a church.
FYI, most of us don't have a place to host our dios. So we go the underground route and email them out. I'm actually cool with this but the audience is smaller than if you operate your own website (ie; Luke Ellison, Violentfix, General Hawk, etc). Self-Modifier is a perfect example of someone actually telling his story 1 page at a time. But even he has now the capability to post his stuff on GeneralJoes.com!
Most of us see Joedios as a hub for dios.