Hey there,
Yes thats a good observation you have made. I love good TV and would watch alot of British TV and alot of US tv. I think you'll find the starkest differences on more of the reality side like Topchef and Kitchen Nightmares. I dont watch these US versions as I find them way too loud and fast paced. The editing is terrible as there needs to be a constant air or drama past, drama present of impending drama and in most cases these scenarios/conflicts are manufactured.
In my opinion, shows like Masterchef UK and Great British Bake Off are by their nature way more intense because there is such a focus on skill and the judging. Thats it too, the judging is not overly harsh 'Gordon Ramsey' style for the entertainment value, it's harsh when it needs to be and it gives praise when it's required. Boht me and my wife love these shows, nothing nicer then watching a new series!
If you love relaxing TV, see if any of Hugh Fearnly Wittingstall's tv shows are on HULU. He's a British chef that did a series called 'Escape to River Cottage' where he leaves London for rural England to pursue a smallholder, self-sustaining life. It was/is a life changing show for me because he inspired me to do similar (I moved from a big city to a rural home and I have chickens!!) But also apart from the cooking element of the show it's got a magically slow pace about it, utterly relaxing to watch and will make you want to jump into the TV and help him with his chores.