First of all there are two categories of blogs. One is the traditional web-log where a web surfer shares his online discoveries. And the second is the web diary where person shares his or her thoughts of the day. Most blogs of either style often have elements of the other style once in a while.
From the weblog of John C. Dvorak (internet/technology commentator/columnist)
This makes much more sense now. Wikipedia has a much more involved entry that lends itself towards the generic, but this makes a useful distinction. So if I'm reading this right (and I'd like to think that I am), the idea is that a "weblog" is actually just that-- a log of the web. Users run into stuff on the internet that they think is worth sharing...and they link it on their blog, often with some bit or two of commentary on the material. Then the livejournal is...hey, what's up, this is what I'm doing today/thinkinga bout. Like Dvorak notes on his explanatory page, certainly this distinction can be blurred, but it explains a lot of things, like why when I search for stuff online, lots of times, I hit "blogs" that have little more than a link and a short bit of text. And here I was thinkign taht that was them just being hacks, that's apparently what the format seems to expect. So I guess that makes this post something of a meta-commentary.