xz XZ is a compressed file format. It incorporates the LZMA compression algorithms. The format can only hold one file at a time. This compression format is used by programs like 7-zip and p7zip. XZ format's implementation is freely available.
rar The .rar filename extension is a popular and partially open archive file format associated with the compression and decompression tool WinRAR. The format was developed by Eugene Roshal with its initial release in 1993. It, like many other archive formats, acts as the compressed data container for one or several files. The archive format can maintain the directory structure of the compressed archive even when unpacked to a directory. The RAR file format supports multi volume file compression where an archive is saved as a sequence of several files of a given size.