TAR and RAR are archiving formats. While files with the TAR extension are uncompressed, RAR files are compressed ones. WinRAR is the primary program used to open RAR documents. On the other hand, TAR files are mainly used by UNIX.

TAR or Tape Archive files are UNIX archive ones which consist of many documents consolidated together. Files which contain similar data can be easily stored together using the TAR format, thus making it easy to create archives. It saves similar files under one name without changing individual settings and preferences. Files are packaged together as one unit and are not actually compressed. On the other hand, RAR files are compressed data ones. They have a high compressed ratio. RAR is a common extension and can be read using a number of applications. RAR can have extensions from R00 to R99 apart from the standard RAR extension. This format is primarily used to compress files which are difficult to compress or have already been compressed. It is very helpful in creating an archive.

The RAR format is very common and hence a number of programs can open it. A few such programs include WinRAR, 7 zip, UnRar, Smith Micro Stufflt Deluxe 2010, Zipeg, and Corel Winzip 14.5. TAR can be opened in applications like EST Soft ALZip, WinACE, Zipeg, 7 zip, Corel Win Zip 14.5 and Smith Micro Stufflt Deluxe 2010.

The common feature between both formats is that they are primarily used to create archives. The primary difference between them is that RAR files are compressed ones while TAR files are not compressed. If they are compressed, they will have the GZ extension. They are compressed in the GNU method while RAR files are compressed using the RAR method.