They are very similar and both serve the purpose to filter out the same size of particles (0.1 to 0.3 microns) and be 95% effective in their filtration. N95 is the name for the masks in the US, K95 is what they are called in China.
Whether N95 or K95, the mask should fit tight on the face or it serves no purpose. If there is any gap or opening, they become ineffective for any filtration.
Always remember, N95/K95 masks protect the wearer from the environment, surgical masks protect the environment from the wearer.
Let’s get technical…so these masks are approved by the Chinese government, are they safe in the US?
Q: Can respirators approved under standards used in other countries, such as KN95, be used in the U.S. during the COVID-19 pandemic?
A: Yes, under an emergency use authorization. The U.S. Food and Drug Administration (FDA) is working diligently to mitigate any potential shortages in the supply chain and taking action to assure health care personnel on the front lines have sufficient supplies of respiratory protective devices. The FDA concluded, based on the totality of scientific evidence available, that certain imported respirators that are not National Institute for Occupational Safety and Health (NIOSH)-approved are appropriate to protect the public health or safety.