The difference between journaling and blogging

I frequently get asked what the difference is between a blog and an online journal or diary. Jesse Chan-Norris, via danah boyd, provides an excellent summary of the history of online journals and blogs and the differences between them. In summary:

Journalers write for themselves, with the audience as a byproduct (even if the journaler is writing with the clear understanding that there is an audience), and the blogger writes for the audience, with the understanding that there is a real person writing an entry.