If you want to create a bootable drive, you need to create an ISO file from the extracted content. Before you can do anything, you need to decrypt and extract the contents. As such, you cannot open them or use them as regular ISO files. The ESD image files are very compressed and encrypted. The developers can then use them to install or upgrade Windows. For instance, Microsoft lets developers download the latest Windows 10 builds in the ESD format. Microsoft uses the ESD (Electronic Software Download) image file format to supply Windows upgrades, updates, and other components.
