Sometimes an אֶפְרָתִ֜ means someone from the Tribe of Ephraim. It is certainly used that way in the context of the "Shibollet" story.
Other times, is means someone from Bethlehem. (Ruth) and (Samuel I 17:12) and is associated with the King David family.
Rashi says it could also mean a generically important person.
Is there a guiding principal to know which use is intended when it is not definite from context?