As far as i understood,
Am i correct or if i wrong please tell me the difference of those two.
Thanks.
The Google Drive SDK is a layer around the Google Drive API; the SDK provides language-specific libraries, examples and guides to ease the development of apps that use the API.
Note that there are currently two versions of the API, with v2 being the current one. You will want to ensure that your chosen library supports the version you're targeting to access the correct set of features.