Nearly nothing. There are differences, but they are small.
Roman society took much from the Greeks when they conquered them. The Romans were more into war then the Greeks (more into the sciences).
Persia was a better place to be a woman than Greece, and they were accepted as professionals (in some cases) in Persia, while in Greece they were confined to the house. Woman were also more important (though still less then Persia) in the Roman Empire.
As well, slavery didn't matter as much in Persia as Rome and Greece.
All three worshipped Gods in what we would now call a pagan religion. The Gods were different but had the same idea.
One of the reasons why most Irish Americans favor neutrality was because they were wary of other immigrant populations entering the country as refugees, which would likely happen if America got involved in the war.
