lets make groups:
tar is for grouping several files into one and doing the reverse
gzip, zip and bzip2 are for compressing a file and gunzip, unzip and bunzip are for decompressing the file
each one of gzip, zip and bzip2 use different compression algorithms more or less efficient depending on the task and what you consider being efficiency (basically compressing speed, decompressing speed or size ratio)
Last edited by Agrouf; 02-04-2009 at 11:08 AM.