ravenford

Haha, I promise I didn't intentionally make my point about how obscure imperial units are in conversion. I looked it up but clearly transcribed wrong!

Well with metric there are alot less words you need to know to use them I think is the point of difference.

Like you need to know that a stone represents a weight, and that that weight is 14 pounds. What's a pound? Oh it's 12 ounces. None of those words are the same out of context but all describe a weight and the size of the weight.

In metric you only need to know that grams measure weight, metres length, litres volume. Then everyday use is normal prefix increments like OP said.

And again the prefixes apply consistently across units too, so a millimetre, a millilitre or a milligram will all be the same fraction of their base.

I think the point op is making is with 'stones' or 'furlongs' etc you need to already know what that unit represents to make sense of it.

With metric units, even the infrequently used increments can be reasoned out just from the name of the unit, as it's a standard prefix in fixed multiples of 10, not a random number that must be learnt.

So they're neither similar or exactly the same in principle really.