Compressing two identical folders give different result

I have two identical folders, with same structure and contents like this: folder_1 hello.txt subfolder byebye.txt folder_2 hello.txt subfolder byebye.txt if I compress them as tar.xz formats I get two different archives with two different file sizes (just a few bytes, but they're not identical). $ cd folder_1 && tar -Jcf archive.tar.xz * $ cd folder_2 && tar -Jcf archive.tar.xz * I get: folder_1/archive.tar.xz != folder_2/archive.tar.xz and of course if I md5sum or sha1sum them I'll get two different hashes And that's my problem... I need to check if a provided archive is identical to the one I have in my storage. I cannot use hashing nor just check file sizes. Using zip instead of tar.xz works as zip always produces identical achives from identical files. Why is this happening? Is there a way to prevent it?