Explained Steps When Building OpenCV Libraries Using CMake

I created OpenCV libraries using CMake a couple of times using tutorials available on the web, albeit without fully understanding the process. Here is the process that I am following

• Configure CMake to generate OpenCV binaries (e.g. with QT, TBB, no CUDA, OpenCL, etc.)
• Generating binaries with CMake
• There are several files in the folder where the binaries are created .sln
  
  . I open the file OpenCV.sln
  
  and run the project ALL_BUILD
  
  for Debug and Release configurations.
• A new folder has been created. bin
  
  Which contains a library (as .lib
  
  well as .dll
  
  for the release and debug versions.
• (Optional) Sometimes I also create a project named INSTALL
  
  (in the same solution), just out of curiosity. I noticed that it creates a different folder where the library files are stored, in the same pattern as the prebuilt libraries that come with the OpenCV package. Interestingly, my programs in MSVC or Qt work equally well if I link to libraries in the folder INSTALL
  
  or the bin
  
  / folder lib
  
  .

My questions

• What is the function of the solution INSTALL
  
  ?
• How are libraries created by the solution INSTALL
  
  different from those in the bin
  
  and folders lib
  
  ?
• Why the solution is INSTALL
  
  not created when the solution is builtALL_BUILD