General :: How To Find All Files Not Part Of Installed Distro

I loaded a distro (which does not seem relevant) onto my laptop and used it for a while. Applications did whatever they do creating and saving files. I know that I have images and documents and videos and music and such on the laptop among other non-distro data files. Is there a simple (straightforward) way to identify which files on disk are NOT part of the installed distro? I know how to use find. I know that find lets me locate files based on some date-time-stamp. I know, too, that I can use any selected file as a benchmark date-time instead of some specific command line string.

For example:
Code:
Find files whose modification date is before (or after) the date(s) associated with the file /path/foo.bar.
Is there any one file that I could use to peg the distro install date? Can I get that date from somewhere else like a file system details?