What is Difference between contiguous set of files and a noncontiguous set of files?

Immediately adjacent. For example, contiguous sectors on a disk are sectors that come one after the other. Frequently, a file stored on disk can become fragmented, which means that it is stored on non-contiguous sectors.

taken from http://www.webopedia.com/TERM/C/contiguous.HTML

So one could assume that the difference is that contiguous files are files that are stored immediately adjacent from one another (together) and non-contiguous files are not stored adjacently hence are separated or scattered.

Hope this was of some help.