There are a few notable differences between KA1 and the P1: KA1 has flexible mic boom; P1 has a wired mic boomKA1 is compatible with both stereo and mono systems; P1 only works with mono systemsKA1 has gel ear seals; P1 has foam, polyurethane ear sealsKA1 includes carry bag for headset; P1 does notKA1 comes with a 5 year manufacturer's warranty; P1 comes with a 1 year manufacturer's warrantyThey both deliver clear, quiet communication and come with durable finishes and sleek design