When is a tar file not a tarfile?

["Robert G. Brown" <bob@xxxxxxx>]

Here's a good situation: 

I have a compressed tar file, and I unpack it in one place....

 tar xzf thisfile.tgz

and then I see how much spave it took up. Let's say it took a 
total of 3.8 MB. Then, I copy this to another linux machine, and 
issue the SAME command. Now, the result takes up about 6.5 MB!
How can this be?!?


                                                              Regards,
                                                              ---> RGB <---