There is no difference in the structure of ISO and IMG formats if the IMG file is uncompressed.
Since the demise of floppy disks, the IMG format has been used for the creation of hard disk image files.
As these sectors are 512 bytes in size, IMG files are always sized in multiples of 512 bytes. It works by creating a bitmap of each sector of the disk that has been written to. The IMG file format was designed to create a backup copy of a floppy disk in a single file. The ISO format was created as a means of archiving discs and as such it has become a standard method of distributing software, such as Linux installation CDs, for users to download and burn their own CDs.
The ISO file format is an international standard file format designed to contain a disc image, including its file system, in a single file.
