Bass-reflex and sealed with passive radiator are both effective subwoofer designs, but they have their differences.
Bass-reflex designs use a tuned port or vent to enhance low-frequency output. This allows for greater efficiency and extended bass response at lower frequencies.
Sealed enclosures with passive radiators, on the other hand, use a sealed cabinet and a passive radiator instead of a port. The passive radiator is a driver without a voice coil, and its movement is controlled by the pressure inside the enclosure. This design can provide similar low-frequency extension as a bass-reflex design but with more precise control and reduced port noise.
Both designs have their advantages and disadvantages, depending on factors like the desired sound quality, enclosure size, and available power. Ultimately, the choice between bass-reflex and sealed with passive radiator comes down to personal preference and the specific requirements of your audio setup.