Select Runtime Library in Windows CE AppBuilder for Compact 2013

When you install the SDK (say the CEPC SDK), you get a folder tree at SdkRootPath. This tree contains two folders with static libraries:

C:\Program Files (x86)\Windows CE Tools\SDKs\CEPC\Sdk\Crt\Lib\x86
C:\Program Files (x86)\Windows CE Tools\SDKs\CEPC\Sdk\Lib\x86\retail

      

        
        
        
      

    

You find MSVCRT.lib

in both folders. The default search order is

• $ (SdkRootPath) crt \ lib \ x86
• $ (SdkRootPath) atlmfc \ Lib \ x86
• $ (SdkRootPath) Lib \ x86 \ debug
• $ (SdkRootPath) lib \ x86 \ retail

What is the purpose of two different copies of libraries?
What's the best practice for choosing the right library?

Edit: The files are of different sizes. Dimensions (in the order above):

• Crt\Lib\x86\msvcrt.lib
  
  2,656,238 Bytes
• Lib\x86\retail\msvcrt.lib
  
  1,717,936 bytes