At the beginning of Ruth (1:1, 1:2, and many others), the place that Elimelech, Naomi and their sons settle in is referred to as שדה/שדי מואב, literally "field(s) of Moab". Why would this usage appear here as opposed to ארץ מואב, the land of Moav? Are they distinct geographical locations?
The pointed Masoretic version says 'שדי מואב' - suggesting literally 'fields of Moab' (although in fact, ) - while the unpointed (ktiv malé) version says שדה מואב - 'field of Moab'.
The fact that the pointed and unpointed are different in spelling, but not in pronunciation, coupled with the fact that the plural of שדה is שדות , so it should have been שדות מואב , suggests that שדי/שדה מואב was simply a placename, not literally 'the field[s] of Moab' – much as "Springfield" is not literally 'field in spring'.
I don't know if there is a distinction geographically. A speculation on my part has been that the narrator intended to contrast Moab with Bethlehem. If you recall Bethlehem means "house of bread" so the writer may have been contrasting the moving of Elimelech's family from one place of bread to another through the use of the "fields of Moab."
Elimilech and his family were Jewish immigrants because of famine in Israel. Their concern was an opportunity to find a place to grow food. Hence they were focused on the fields of opportunity. "Land" has the double meaning of "country" so perhaps the author was stressing that it was the fields that drew them to Moab.