Differences between wikis and blogs

I am having fun working with wikis and blogs. There is so much that one can do with both that it is rather overwhelming. The main difference that I am finding between wikis and blogs is that anyone can change any wiki page that has not been locked. This is scary to me. When I was added the links to my blog and my wiki to the class lists, I could change that whole page if I wanted to. As one of the instructors stated in an email to us, someone had alphabetized the lists. That was a very nice thing to do. The point of starting a wiki would be to allow others to add and edit pages. This facilitates communication and collaboration. With blogs, you can communicate with the author but only through the comments. You cannot change anything on the blog itself, which you can do with wikis. A blog would be used for information purposes, like library policies, hours, holiday closings, etc. A wiki can be used to communicate among staff members, or even between faculty members and library staff.