There are a few key differences between PDF and PDF E:
PDF is a file format that can be used to represent documents in a fixed layout, much like an image. This means that the formatting of the document is preserved no matter where it is viewed, making it ideal for sharing documents electronically. PDF E, on the other hand, is an ISO standard for electronic documents that preserves the appearance of the document across different devices and platforms.
To convert a document to PDF E, you'll need to use special software that adheres to the ISO standards. Once your document is in PDF E format, it will be more portable and viewable on a wider range of devices.