The AutoCAD Map 3D SDK includes ObjectARX, ObjectARX .NET, Feature Data Objects (FDO), and Geospatial Platform .NET.
ObjectARX is an unmanaged C++ API. ObjectARX .NET is the managed C++ equivalent.
FDO, like ObjectARX, comprises both a C++ API and a managed C++ equivalent.
The Geospatial Platform is exposed as .NET only.