ArcGIS Explorer Desktop is a GIS viewer that gives you an easy way to explore.
ArcGIS Engine is a complete library of embeddable GIS components for developers.
It is a set of tools for ArcGIS that enable the users to create surfaces.
GTP for ArcGIS the functionalities of ArcGIS to more than 90 raster formats.
It is a plug-in that provides interoperability between AutoCAD and ArcGIS.