What is really the difference between a blog and a wiki...
...if you don't write about what you had for breakfast, that is?
The first answer that springs to mind is probably "a wiki is made to be edited by multiple people, duh?". But if you lock the wiki for editing only by yourself, you've got a blog, no? Let's be more systematic though and start with the (informal) definitions.
What is a blog really? A collection of articles sorted by time (newest first) and searchable by content, keywords or tags, with a mechanism for user comments. What is a wiki? A collection of articles (hopefully) up to date (hence posting date won't matter much), searchable by content or tags, where user comments are weaved directly in the article (aka "collaborative editing").
The main differences, then, appear to be these:
I blog about things that interest other people as well (isn't that the point of publishing?) and even though I write opinion posts, I don't exclusively do so. Many of my pieces are howtos, to which others are invited to contribute and improve. Thus, I don't really care about sorting my articles by time, although I can certainly do that by listing them in a Table of Contents along with the date of initial publication. That takes care of difference #1.
- relevance of posting date
- separation of user comments from article content
As I discover more information on a topic I wrote about, I'll need to edit my blog posts. Editing is a wiki activity. Would I mind if someone else improved on my blog post / wiki article? No, not really. It's still written mostly by me and appears as such immediately if one goes to the revision history.
Are here enough reasons left to justify maintaining a wiki and blog separately?