Hello @FattyBull ,
I don’t know much about your mesh or export process here, but generally speaking, most other programs will not be able to work comfortably with meshes at the sort of extreme polycounts that ZBrush does. In these cases you will have to export a lower-poly version of the mesh, capture the surface detail as a displacement map, and apply that map in your target application for rendering.
In the case of losing detail when viewing a mesh at the same level of resolution in both programs, this probably comes down to a difference in material (shader), and the presence of some sort of poly smoothing effect.
The ZBrush Red Wax material has characteristics that enhance the look of fine detail. In addition, in most circumstances in ZBrush you are viewing the actual surface of the mesh free from any procedural smoothing effects. You will see the actual polygon facets until the mesh is subdivided sufficiently to smooth it. This may not be the case in another program that has some sort of smoothing effect active to give the appearance of a smooth mesh even at lower mesh resolutions. The tradeoff to this sort of effect is often a loss of fine detail from the surface of the mesh.
Good luck! 
