Both handle gigabit internet really well, which is the highest speed that most people will get from their internet provider. The AX6000 has a couple of additional ethernet ports but the real difference is the antennas for 5GHZ, which is what most devices connect to. The AX6000 has a 4x4 antenna setup and the AX4200 has a 2x2. Whether you will benefit from that depends on the devices you have and how many of them you have. Larger, more expensive devices may have 4x4 receivers that can take advantage of the extra antennas simultaneously and get really fast speeds, but most devices like phones, tablets, TV’s etc. are 2x2 or even 1x1. So, the main benefit comes in with the more devices you have. With twice as many antennas, the AX6000 can more easily handle more devices. Bottom line, if you have just a few connected devices, you will see zero difference between the two. If you have a lot of people in your household or like 40 devices in your house trying to connect, the AX4200 would still work fine, but the AX6000 would provide a noticeable performance boost.