Hi Michael,
Thank you for your reply. Yes, my understanding of their usage was not clear as well. Thank you for clarifying it.
So for version 10.3, I think the one that is similar with ArcObject SDK, that can make add-ins to extend the functionality of ArcGIS Desktop, will be ArcGIS Pro SDK, right? It is just that ArcGIS Pro SDK only works for ArcGIS Pro product customization. So for the other ArcGIS Desktop product, say ArcMAP, does it mean ArcGIS 10.3 will still have ArcObject SDK for ArcMap 10.3?