What I think it means is that the Easychange holder is left in the spindle and you then have chucks with a quick-release taper that clip into the holder. My Novamill has a BT30 spindle taper and an Easychange holder that fits in that – then it came with 2 ER16 collet chucks.
In practice the Easychange holder eats too much daylight and the chucks with the proprietary clip-in taper cost ££££! So I hardly ever use the Easychange system, I got a couple of BT30/ER16 chucks off eBay, but seldom change tool by having them preset in a another chuck. If there's a drawbar it indicates the holder should be removable, sounds like it's been left in and has seized a bit.