What is the differences between Sync Framework 2.1 SDK and Sync Framework 2.1 Redistributables?

I'm new to MS Sync Framework and get confused by the two packages to download from MS Download page. Please explain if you know the diff开发者_Python百科erences.

The SDK is fpr developers, the redistributeable is for client pcs.
Here's a C++-example:
SDK: Headerfiles + Implementation (C/C++-Files) + DLLs to link with + ...
Redistributeable: DLLs which are needed in the compiled version of your programm