Well sure, but I think we can reasonably limit this discussion to a system where all else is equal except for sealed vs. bass reflex. In that instance, I think it's fair to say that the bass reflex enclosure will be substantially more efficient (up to the port's tuning frequency, of course) compared to the sealed one. Again, happy to be corrected though.
It will be more efficient in a relatively narrow band around the port tuning yes. But in this day and age many sealed subwoofers use DSP to alter their response. This means that while they're less efficient, they can (and often will) have just as deep bass extension as the ported subwoofer. So with both subwoofers playing within their capacity, they will have just as much bass.