The exact inlet locations and names have changed with time, as new inlets open, merge, or close. Conversationally, the inlet or inlets between mile 19 and 23, as measured from Ocracoke Inlet, are typically called Drum Inlet even when, geologically, they have other names.
In a geographical context, the inlet locations have changed over time due to various factors such as new openings, mergers, or closures. The colloquial term for the inlets between mile 19 and 23 from Ocracoke Inlet is Drum Inlet, even though they may be referred to by different names geologically.