Manila is so much more ambitious. It keeps your stories and your graphics in its database and serves them up as dynamic pages. It allows you to create a discussion forum on every story you post. It signs up members for you and remembers them. Both Blogger and Manila anticipate that there may be several people updating the same site.
Manila aspires to be a complete web-publishing system.
And it was only released on December 1st. All that being given, I still have some problems with Manila. Hard thing are easy and easy things are hard. I still have not figured out how to know whether a story I have written will appear on my home page or in the Calendar archives. The model is so flexible, I wrote a story that disappeared.