No, just the style of the stoker. I believe the boiler blank is smaller also, but I have no tech sheets on the boiler itself. Duplicity was the original reason to retire the old KA 4, especially with the KA-6 so close in size. However some folks wanted an output just the size of the new Kaa-4-1, since the Kaa2 would struggle in very cold weather. LL and the 110 boiler met that demand, so with the Kaa-4-1 in testing anyway, let the prototype make a production run.