Wikis are more likely to be monitored by more people but at the same time it can be edited by multiple people as well. Usually wikis are meant to be more informational/educational. When in need of information some would like to go to a wiki to find it. The problem is that as spoken about in the New York Times article, "An Internal Wiki That's Not Classified", it is likely to come across "disinformation or vandalism". It is so easy for one to put up the information they think they know or don't know that it can very lead to having misleading information.
They are similar because they are easy to utilize and they allow people to share information with others. There aren't really any requirements or credentials to create a blog or a wiki. They both have the purpose of sharing information but they both have their cons to them which can interfere with their purpose. Blogs can be used to collaborate by having, say a manager start a blog. He can post something for his employees to respond to(meetings, ideas, assignments, etc.) Blogs allow a better interaction between the blogger and the audience and it's close to having a conversation. A wiki can maybe be used similarly like a blog where certain opinions can be shared and those that are similar or overlapping can be grouped together. All of it would fall under a topic of discussion as opposed to it being strictly facts put in front of you, but it might not be convenient.
