I'm one of those who feel very different riding a western vs English (or Australian) saddle. My western saddle is shaped differently - much wider. It places me further back, and I lose contact between my lower leg and the horse. It IS possible to ride it with lower leg contact, but harder because of the shape of the saddle.
Western is more seat, while English is more leg - at least to me.
Some of it is psychological. When I go from my Australian-style saddle, with poleys and even a horn, to my English one, the SHAPE of the saddle feels the same...but I feel naked without the 'stuff in front'. No, I do not hang on to the horn. I can't remember the last time I made contact with the poleys, and my Aussie style saddle is arguably "cleaner" than my English one, since it has no knee pads.
But mentally, going from this:
Makes me double check to see if I've left the house without my jeans on...