They're mostly identical, but from different countries.
As far as how well they protect against COVID-19 and filter out particles, a KN95 and N95 are the same. But there are a few differences on other fronts.
- KN95 meet Chinese standards for masks, while N95 masks meet US standards.
- Every country has its own standard. Ex. KF94 is the Korean code, FFP2 is the EU and UK code.
- Both KN95 and N95 masks are rated to capture 95% of tiny particles (0.3 micron particles).
- Both KN95 and N95 masks fit tightly around your nose and mouth.
- KN95 mask manufacturers are required to run fit tests on humans with ≤ 8% leakage, while N95 masks are not.
- N95 masks have slightly higher restrictions for pressure drop while inhaling and exhaling (read: better breathability).
To learn more about KN95 and N95 masks from the FDA, read their FAQ.