Debbie has an interesting post comparing blogs to message boards and has developed a "10 Ways Blogs Are More Effective" list. I'm going to help qualify her post: Yes, blogs are a more effective mean of communication if you're a company or person that is trying to convey a message and solicit feedback from readers.
Realistically, though, it's not comparing apples to apples. For example - boards are a much better way to learn about a community and gain insights on current products, usage, future product development and even customer servicing issues. Blogs can't do the aforementioned as effectively.
You might think wikis have helped take care of the need for FAQs, however as a bass player I've received more knowledge and friendly advice from the guys and gals on Talk Bass than any blog. The ability to post a question and get an answer within a minute is something blogs can't offer. Are they risky? Hells yeah they are. Just ask Yahoo. In fact, aside from tech brands very few companies have owned the content, distribution (and legal headache) of message boards.
Take the auto industry, for example. The top auto boards aren't owned by the Big 3, Toyota or Honda, but by enthusiastic webmasters that set up the fan sites using their own time and money. Scion Life, for example, is run by two guys - Darren and Troy - neither of which are Toyota employees.
Back to the original point - and I think there's an ad campaign using this slogan, but I'll use it anyway - what makes them different is what makes them great. Saying one is better than another requires a qualifier, sho'nuff.