Difference Between NRG and ISO

The images in the disc are saved in various formats. There are several applications to recognize disc images. The formats play an integral role in the backup of important data.

There are two main file formats available – NRG and ISO. Though both the formats seem similar, they have distinct differences.


The main difference between NRG and ISO is that NRG is a disk image format that was developed by Nero AG while ISO is a disk image format that was developed by OSTA (Optical Storage Technology Association). NRG is a proprietary format of optical disc image while ISO is a global standard.


NRG is a popular and common disc imaging and burning software. NRG has two versions. The file extension of NRG format is .nrg.

The storing format in NRG is not in the header but in the footer form, which is at the end of the file.

On the other hand, ISO is a globally accepted and recognized disc imaging and burning software. ISO has only one version.

ISO images contain binary images of the file system. ISO file can store the user data which is received from each sector of the optical disc.

Comparison Table Between NRG and ISO

Parameters of ComparisonNRGISO
Uniform Type Identifier (UTI) com.nero.nrg-imagepublic.iso-image
File extension .nrg.iso and .urg
Type of format Disk imageDisk image
Developed by Nero AG OSTA (Optical Storage Technology Association)
ApplicationUsed to store disc images and in a variation of IFF (Interchange File Format) Used in emulators such as Dolphin and PCSX2 to replicate the image of a CD, as virtual CD-ROMs for hypervisors and for burning disk images of OS to install media

What is NRG?

NRG is a proprietary format of the optical disc image. NRG was created and developed by Nero AG for the utility of the Nero Burning ROM.

Nero is a common and renowned software for disc imaging and burning. Nero gives programmers an incentive and pedestal which can support the other file formats.

This helps the programs to open the disc images that had been created in Nero.

NRG can be used in several other software titles as image files. The file extension name of NRG is .nrg and the UTI (uniform type identifier) is com.nero.nrg-image.

NRG can store audio tracks which can be used in audio CDs. NRG is one of the few formats that have the potential to support Mixed Mode CDs. These Mixed Mode CDs can contain audio tracks as well as data tracks.

NRG file format has a great application in the variation of IFF (Interchange File Format). In this format, NRG can store data in a form of a chain of chunks.

The integer values which are stored are in an unsigned form and byte order. The earlier version 1 of NRG could store only 32-bits integers and the new version 2 can store up to a 64-bit integer.

Version 2 was introduced by Nero Burning ROM v5.5.

The storing format in NRG is not in the header but in the footer form, which is at the end of the file. All the image formed, is stored in a serialized chain of IFF chunks.

The NRG footer begins by reading every first chunk from the last 8 or 12 bytes. There are also fixed-size blocks called CUEX chunks which are present in all versions of NRG file format and represent a cue point.

What is ISO?

ISO is a standard global. It is created by ISO which is a body that is responsible for governing over the world standards. ISO is compatible with most of the software.

It has worldwide acceptance. It is a file system that was mainly used with CD-ROM media.

images contain binary images of the file system which is generally optical disc. Most of the data in the field are copied on the binary format on the disc.

The structure of the data is done according to the file system. The file extension of ISO is .iso and .udf and the UTI (Uniform Type Identifier) is public.iso-image.

The internet media type of ISO is application/x-iso9660-image.

The creation of ISO images can be done from optical discs.

There are various disc imaging software, different disk image files, or collection of files by optic disc authoring software which helps in the conversion and creation.

The bootable disc contains software that is distributed, can be downloaded in ISO image format.

ISO file can store the user data which is received from each sector of the optical disc. It ignores the control headers and data of error correction.

The file stored is smaller than the raw disc image of the optical image. The size of the ISO image is a multiple of 2048. The opening of the ISO image is done through a multi-format file achiever.

Main Differences Between NRG and ISO

  1. NRG is less compatible with other software while ISO is more compatible with other software.
  2. NRG is not incorporated in the most operating system while ISO is incorporated into most of the operating systems.
  3. NRG needs installation of other software to burn images while ISO does not need installation of any other software to burn images.
  4. NRG can record discs and multiple audio tracks while ISO cannot store audio tracks.
  5. NRG does not offer the highest level of portability while ISO offers the highest level of portability.
  6. NRG has two versions – compressed and uncompressed while ISO has only one version
Difference Between NRG and ISO


Both the formats are archival. Every file of the format contains copies of the original disc. The contents of the original disc contain information and file structure.

The main point of distinction between both the file formats is their source.

Both the formats, NRG and ISO, have different developers and different areas of application. The storage format and size are different from each other.

Both the formats have different versions. Both formats play a pivotal role in burning a duplicate CD easier.


  1. https://www.cheescube.com/open-access/security-issues-in-protecting-computers-and-maintenance-55-58.pdf
  2. https://ieeexplore.ieee.org/abstract/document/4667573/
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