Not much......You can actually have a spray lance and/or an extension lance. A spray lance will have some sort of nozzle on the end and an extension lance just extends/adds on to the length of the spray lance.
An AR brand extension lance will not work with any Karcher electric pressure washers.
Follow the links below to find extension and spray lances for Karcher electric pressure washers. See below:
Karcher Spray Lances
Karcher Extension Lance
Let me know if you have any further questions.