Seth, I would GUESS your deer at 3&1/2. 180, I'd guess yours maybe 4. now, 1) I could be WAY off because there's always freak examples where I'm WAY off. Off by several years. Now, on average, deer of certain ages have certain characteristics, sometimes they are often BUT MOST OF THE TIME they are accurate defining characteristics. Just like most guys with gray hair and severely bald are 60+ but you all know that guy who is like that at 40. Nothing is EXACT.
2) for BOTH those deer, I really would like to see FULL BODY shots, obviously standing is best, I'd want to see shoulders, belly, swaying in back, etc. I'd ALSO like to know what time of year they were shot. Your 6 year old buck is gonna have a whopper of a body in October and could shrink CONSIDERABLY by December- RUT.
Again, no exact sciences, many variables, much experience required BUT you can attribute traits and characteristics closely to age. IMO
*I suspect those pictures may have been posted because they are extreme examples of looking different than their age truly is???? Totally cool to show those examples though!!! Great deer too!! Always extreme examples on every farm, please don't think I'm saying different. We're talking about general characteristics, typical situations but NOT exact 100% science and guarantees.
*See buck in my avator (or whatever it's called), not a great example BUT in the big photo you can see all the loose skin- you can still see it in his neck/shoulder (look close), big hanging belly, swaying back and other angles show long defined snout + RACK. i know the deer very well over the years. What's the guess???? (and yes, once you get past 5 yrs old it's darn near impossible). He's 6&1/2. I'm not surprised by that and I find it consistent with a 6&1/2 year old buck (or any FULLY MATURE BUCK- most 2, 3 or even 4 year olds won't have all those defining characteristics).