from datetime import datetime

start_time = "10:44:09.339931"
end_time = "10:44:09.376233"

t1 = datetime.strptime(start_time, "%H:%M:%S.%f")
print('Start time:', t1.time())

t2 = datetime.strptime(end_time, "%H:%M:%S.%f")
print('End time:', t2.time())

delta = t2 - t1
ms = delta.total_seconds() * 1000
print(f"Time difference is {ms} milliseconds")