Photo Blogs, Discussions and Documents are all quite similar to each other as they are all based on KeepandShare's powerful document editor.

The Discussion document editor window is smaller than in the Document application, because the "starter document" you begin a Discussion with is typically just a few sentences long.

Otherwise, Discussions are quite similar to documents, but by having a separate "application" area, you can keep your online discussions organized separately from your permanent documents. Hence you can click on the gray tab "Discuss" to see all of your Discussions, and click on it's "Document" button to see all of your permanent documents.