Answer:
The main difference is what the terms "region" and "period" are referring to.
Step-by-step explanation:
A historical region refers to the geographical areas traditionally associated with a people, society or nation with specific features that are manifested in cultural elements of an area, especially the language and architecture, and with which its inhabitants identify during a historical time determined. On the other hand, the historical period refers to the time of a historical event that marked a region, such as Ireland's great famine.