An example of a story that progressed from breaking news into follow-up is news on the Costa Concordia.
When I first blogged about it, I used the Associated Press and CNN as sources for my blog. The 'breaking news' concept was that salvage was given the go-ahead. Whereas now, the stories that make the news about the Costa Concordia are about the passengers.
For example, the newest news stories on the Costa are about the missing couple from Minnesota.
The follow-up stories are more likely to be profiles on victims. They advance the news by bringing in more detail and personifying the events, or expanding on stories from competing news organizations.
In breaking news, the lead is a hard, one sentence summary of the article. Breaking news also tends to follow the inverted pyramid.
Follow-ups are written much more freely, and don't need to hit all the hard news right away.