It's a tough one, for some reason.
I've tried to compare the two many times, but inevitably I end up comparing 7 m.o. Baby Miles with the great dog that Ari grew into in his adulthood (despite his wild and long teenage period), and of course it's not a fair comparison.
But - still, some earlier memories are still alive, and so some comparisons can be made.
Both - stubborn, as Ridgebacks are expected to be.
But Miles is willing to push the boundaries and limits much further. The most flimsy fence or barrier was enough to stop Ari from crossing. Miles keep pushing and pulling and trying, until he finds a way to create an opening and squeeze through.
Ari was a very quiet dog, Miles is very vocal. If a human got distracted and took extra 5 min to give Ari the 2nd half of his meal - 5 min later he would find Ari sitting in front of his empty dish with sad eyes, waiting.
Take extra 20 seconds with Miles - and the neighborhood will be awaken by loud howling.
Ari valued personal space. He always wanted to be near his humans, but yet needed space. If he was sleeping on a sofa, and a human got on the same sofa - Ari would get off and settle in the armchair, or moved to his own bed. Baby Miles says "Great!" and squeezes himself in next to the human, or sometimes on top of him.
On more serious traits - at 7 m.o. Miles seems a LOT friendlier towards humans and dogs. This is where my memory starts failing me. I know Ari became horrible with dogs at some point, and it took a very long time (and a lot of 5 AM walks) before he mellowed down. But I don't remember when this started. Probably later than 7 months, so the jury is still out on this.
But in the meantime - we truly enjoy our walks and his interactions, with humans and dogs of all kinds. Granted, not everyone appreciates a 35 kg 7 m.o. puppy - but he still assumes everyone is his best friend, and is quite gentle with small dogs, and with small humans too. During walks we encourage everyone who wants to come and say hello to do so - children, adults, all kinds of people, and he enjoys most of the encounters. I think Ari tolerated much more than he enjoyed them, back in the day.
The biggest difference in what we are doing I think is "NO DOG PARKS" rule we have for Miles. He has several playmates, with whom he runs and plays whenever there is an opportunity, and it works great. Those poodles, and we have a 2 y.o. Pitbull girl a few houses down the road who is almost as big as he is, and faster than him. When we meet during morning walks - we let them both of leash and they chase each other - yes, through other people's font and back yards - wrestle, explore, run after squirrels and chipmunks… Good thing we both walk our quadrupeds quite early, most neighbors are still asleep
But with strange dogs we meet in parks or in town - we keep on-leash encounters short. Either both off leash so they can interact unrestricted, if it feels safe, or we move on.
Other than that - I don't know if we really changed much.
So far - fingers crossed, he is a very sweet boy, but I am sure the worst is still to come.
This would be unimaginable with Ari, but routine with Miles:
And they sure do look similar! Ari (left) and Baby Miles (right)
And one more thing is unfortunately very clear too - 8 years between them is a long time. Everything is harder - getting up in the middle of the night during housetraining was harder, waking up and going out for early morning walks is harder, just running around the back yard and playing with the puppy is harder. Can't beat the time.