What's the difference between Page Not Found and File Not Found?

When I visit mysite.editme.com/SomeNewPage, I get a Page Not Found screen that prompts me to create the page. But if I visit mysite.editme.com/SomeNewPage.html, I get a File Not Found page named "404" that I can edit. What's the difference?

EditMe looks at the requested resource (the URL) and determines whether it's a valid page name or not. For example, sometestpage is a valid page name, while sometestpage.txt is not.

The 404 page is used for non-EditMe page resources that are requested but do not exist. Since it's not a page name, it can't be created, so a 404 status is the appropriate response. The 404 page simply lets you customize the message users see when encountering a  404. This is mostly in place for customers who migrate a non-EditMe site to EditMe and want to handle old URLs like /company/aboutus.html.

When you visit a valid page name that doesn't exist, EditMe prompts you to create it if you have the sufficient access rights. If not, it prompts you to log in. This page cannot be customized currently.