The LEVOIT Core 400S-P and Coway AP-1512HH both deliver effective air purification, but they cater to very different needs, primarily defined by coverage area and smart features. The most striking difference is the LEVOIT Core 400S-P's monumental coverage of 1733 sq ft in one hour, dwarfing the Coway AP-1512HH's 375 sq ft. This makes the Levoit an ideal choice for large open-plan homes, lofts, or even multiple connecting rooms, while the Coway is best suited for single, smaller spaces like bedrooms, offices, or studio apartments. This means buyers get significantly more coverage and modern features for less money with the Core 400S-P. The Levoit also integrates Wi-Fi connectivity and app control, offering real-time PM2.5 monitoring and remote operation, features entirely absent from the Coway. For those building a smart home ecosystem, the Levoit is the clear choice. In terms of core purification, both utilize HEPA filtration. The Coway boasts 'True HEPA' filtering 99.999% of 0.3-micron particles and explicitly reduces 99% of VOCs and odors. The Levoit, with its 'HEPA' filter, targets 99.97% of 0.1-0.3 micron particles. While Coway's specifications might suggest a marginal edge in particulate removal or VOC reduction, both are highly effective against common allergens and pollutants. Noise level is another differentiator; Levoit explicitly notes a quiet 24 dB in Sleep Mode, making it less disruptive for bedrooms, whereas Coway's quiet operation is implied by its Eco Mode but lacks a specific decibel rating. The Coway's Eco Mode, however, is an excellent energy-saving feature, pausing the fan when air quality is good, a direct benefit for electricity conscious users who might not need constant operation.