Indeed if the same processes are considered there should be no difference. But you have also to consider that the implementation of CeD or Cex on SIMA might differ from other calculations or software. there is also the unceratainty asociated to the implementation of the database. So a difference might appear due to these two factor and not due to the methods on its self.
you can have an example of CED applied to buildings in my paper:
F. Asdrubali, C. Baldassarri, V.Fthenakis: “Life Cycle Analysis in the construction sector: guiding the optimization of conventional Italian buildings”, Energy and Buildings, 64 (2013), 73-89