UNIX is a multiprocessing OS that is well described in the literature. Linux is a UNIX kernel written by Linus Torvalds.
Slackware, Red Hat, Suse, etc. are just distributions of the Linux kernal that are based on GNU software, all developed for the UNIX operating environment (long before linux was on the planet.)
Sun OS, Solaris, AIX, etc. are also based on UNIX kernels. The environment can be built on GNU software as well.
There is nothing common with AIX, SunOS, OSX, HPUX, SGI, ULTRIX, FREEBSD, etc. etc that is not common with LINUX. They are all based on the philosophy of the UNIX OS.
In fact, there is nothing useful in grouping all non-Linux OSs under the UNIX flag and dividing it that way on this site.
None of this has anything to do with TIFF files.... so lets move to TIFF. The philosophy of UNIX has been discussed many times in the threads.