The orientation development of nanotubes (NTs) during flow of nanocomposite melts was studied in elongational as well as shear flows. Two types of NTs were included in the investigation: Multi-Wall Carbon Nanotubes (MWCNTs) and Tungsten di-Sulfide based Inorganic Nanotubes (WS2-INTs). INTs differ from CNTs with respect to its diameter (100 nm compared to 10nm) and length (1 micron compared to a few microns). Distinctively, pristine INTs surfaces are rich in sulfur and tungsten elements with a small fraction of oxygen. CNTs surfaces are composed of aromatic moieties that lead to agglomeration. The surface attributes of these two classes of nanotubes effect their rheological properties and dispersion in polymers. As the orientation of the NTs is the decisive factor determining the final nanocomposite properties (mechanical, thermal, electrical), it is of significant importance to study the mechanisms of orientation development of NTs containing polymer melts. The orientation state of the elongated NTs is governed by two principle flow fields that prevail in all processing methods namely: elongation and shear flows. Experimental results and derived modeling showed that the orientation development in elongational flow is enhanced in the case of INTs compared to CNTs as is the case in shear flow. A rigorous analysis of the time dependent orientation indicates that while the INTs demonstrate rigid like behavior the CNTs are affected by the relaxation of the host polymers. In addition, the formation of agglomerate structures in the case CNTs should be taken into account with respect to the orientation development. Based on the orientation state and resulting morphology a generic engineering design methodology and modeling could be formulated for the prediction of the final polymer nanocomposite properties.