Actually, I think the two systems are pretty close in volume measurements such as fl. ounces, cups until it hits pints: then the big difference is that ours contains 16 ounces while yours contain 20 ounces.
The two systems are similar but there are plenty of differences, mostly small, but also we both use some extra odd units such as your 'stone' weight which is 14 lbs. Also, if I am not mistaken, you (UK) apply specific measurements to specific items being measured, again stones is used to define a human's weight but you do not buy, say, potatoes using 'stones' but rather pounds.
I believe our 'tons' are different too although it might be a matter of semantics. When an American uses the weight term 'ton' we are always referring to 2,000 lb. I believe the UK may use what we call the 'long ton', 2,240 lbs. but am not sure how you refer to it.
Our 'barrel' sizes are different also, although a 'barrel' is not a useful definition without more info.; a barrel of oil is a different size than a barrel of water, or a barrel of wine, or a barrel of whiskey..... I think.
As the story goes: the Mayflower could not wait for correct water barrels and so used wine barrels to store water for the journey to America. After arriving, they assigned UK gallon measurements to the wrong number of divisions coming out of the containers. And so that is where and how 'our' two systems started to part ways. Great story.... incorrect but still a great story.
Hat sizes in the US are something like 3/8" smaller than the UK due to the original hat blocking equipment being miss- calibrated in the US.
Clothes sizes are beyond my ability to comprehend, especially women's sizes (and girls, and junior- miss, ad nauseum) so I have no idea.
After that, most measuring metrics (not metric though) are so odd that I think everyone has to look them up; rods, chains, fathoms, furlongs and so forth are just not anything to most people remember well enough to use conversationally or scientifically.
Brian
Besides the US Gallon which is smaller than am Imperial Gallon (which also means our pints are bigger as is anything else linked to the gallon) what other measurement differences are there between Imperial & US?
I think spoon size might be
Cloth sizes certainly are