Tar relates to a file format widely used in UNIX environments, identified with the extent of tar. It also refers to the program for managing files that are standard in these environments. The format was designed to store files in a convenient form on magnetic tape and then comes its name, which stands for "tape archive". Due to this origin the format is ready to be processed linearly, without a way to remove a member without traversing the entire file to find it. Initially developed to write data to I / S sequential devices for purposes of backup tape, tar is used today to collect many files into one larger for distribution or archive file, while preserving the information system files, such as user permissions and group dates, and directory structures.
Bzip2 is a free program developed under BSD license that compresses and decompresses files using compression algorithms Burrows-Wheeler and Huffman coding. The compression ratio achieved depends on the contents of the file to be compressed, but usually is far better to compressor based on the algorithm LZ77 / LZ78 (gzip, compress, WinZip, PKZip, ...). In return, bzip2 uses more memory and execution time.