On OSX and Windows, as you might know, directories are case insensitive. So the directory CaseSensitive and casesensitive are the same on those operating systems. But on Linux, they are different directories.
The interesting thing about this is, that when you use docker and attach a volume to the container from OSX or Windows, that directory will be case insensitive. While other directories within the container are case sensitive (because it runs Linux). Which makes perfect sense, as the directory in the volume is managed by your own OS.