The sagging belly and the overall size difference between the 7 and 8 in pics I have of them standing beside each other is what makes me think there is at least a 1 year age difference
I'd like to see a pic of the 7 pt when he fills out and at a little better angle. I keep coming back and looking, and it wouldn't surprise me if he is 4.5. It's hard to tell this time of year before they fill out all of the way.