Well, in Harvest Moon New Story, we can probably expect new farming mechanics. Maybe new types of crops to grow and different ways to take care of our livestock.
No, they're not the same. Story of Seasons is a new series that developed from the Harvest Moon franchise but has some distinct features and gameplay differences.
They aren't identical. Harvest Moon was the original, and Story of Seasons is a continuation with its own tweaks and improvements. The worlds, quests, and overall feel can vary between the two.
The social aspect might be different. In this new story, there could be more complex relationships with the villagers. For instance, we might have more dialogue options and different ways to interact with them, like joint projects or helping them with unique problems. Also, the layout of the farm might be changed, with new areas for different activities such as a special greenhouse or a new fishing spot.