Hi,
I found that there are different DRC rules for Poly and Dummy Poly. For example Dummy Poly and Dummy OD can overlap, while Dummy Poly cannot overlap with OD.
Re: Are there any differences between Poly and Dummy Poly material?
No, it's the same material (poly silicon, doped). Different DRC rules, because in one case - additional to lithography and process determined - also electrical rules have to be obeyed, whereas for dummy poly the latter is not the case - dummy poly has just to ensure uniform material-related environment conditions.