"And God answered her: There are two nations etc." For Shem the son of Noah, the Holy One Blessed Be God said, that he will tell her there are two nations in your womb. "There are two nations in your womb." This is Rabbi Yehudah Hanasi and Antoninus, who did not lack for anything on their tables, neither a radish nor horseradish, neither in the days of sun nor in the days of rain. "Two separate peoples shall issue from your body."
From the innards they shall be separated one from the other. "One people shall be mightier than the other." Rome was destroyed and Jerusalem remained, Jerusalem was destroyed and Rome remained. And similarly it is stated,"Now that it is laid in ruins." (Ezekiel 26:2) If one is in ruins, the other will be destroyed too.
Another interpretation: princes from Jacob, kings from Esau, kings from Israel, chiefs from Esau. This like what it says, "these are the kings." (Genesis 36:31) "The older will serve the younger", Esau will serve Jacob.