Like Kris explained, these are the same libraries created for different use cases. I hope you know already, that a library in C++ can be linked statically to a project or loaded dynamically during runtime. Here
http://www.boost.org/doc/libs/1_54_0/more/getting_started/windows.html you can find an explanation of the different lib names see 6.3 Library Naming.
If you wanna use a library in your application you have to specify the path where the compiler will look for libraries and you have to define which library you want to use. How and where you define these values depends on the IDE (Eclipse, Visual Studio, XCode) you are using. Usually there is something like Linker Flags where you define which library should be linked and Library Search Path where you specify where the compiler will look for additional libraries, at least in XCode.
I link the boost libs statically to my projects, because otherwise the .dll files for the libs I used must be delivered together with the binary which I don't like so much.
Cheers
Georg