The MODIS 3 km dark target product contains parameters (SDS) for both land and ocean.  
All parameters within this file are the same as those available in the 10 km product.

The differences between the 3 and 10 km products are in the algorithms used to create the products and the size of the output file.

The differences in the algorithm process are:

1.  The size of the pixel-arrays defining each retrieval box.  20 x 20 half kilometer pixels for the 10 km retrieval vs 6 x 6 half kilometer pixels for the 3 km retrieval.
2.  The minimum percentatge of "good" pixels required for a retrieval.
3.  The 10 km algorithm will attempt a "poor quality" retrieval when the number of available pixels after all of the screening procedures is small. The 3 km retrieval will not attempt a retrieval under these circumstances.  This means that in the 3 km product there will not be retrievals with a QA of 1 or 2 over land.