Twin step hull on the Lightning vs single step on the Ex. The Lightning is several mph faster with same power. Cockpit is a little nicer on the Lightning and the cabin is a little taller.
Usually but not always. There is one Ex for sale with 525s and I've seen a few with 500 efi's. There are several Lightnings with 496 HO's, a couple that are owned by board members.
If you are over 6' tall you won't like the seat position of the Ex. It is real close to the dash. I don't know if it is diff in '05 but it was a lot closer on an '03 I looked at vs. my lightning. That was the deciding factor for me.