Grem56 - I think the distinction between “mold” and “mould” is yet another example of “two cultures divided by a common language.”
The American Heritage Dictionary (my personal favorite, but I’m hardly free of bias) lists three separate definitions for the word “mold.” In abridged form, they are: “1. A hollow form or matrix for shaping a fluid or plastic substance…” “2. Any of various fungi that often cause disintegration of organic matter…” “3. Loose, friable soil, rich in humus and fit for planting…” Each of those definitions goes on at some length, but you get the picture. That same dictionary defines “mould” as "Chiefly British. Variant of mold."
I have to deal with British publishers and correspondents now and then so, in a futile attempt to avoid embarrassing myself, I keep a paperback copy of The Oxford Dictionary of Current English by the computer too. (“Current” in this case means 1990.) It gives three definitions for “mould,” as follows (again in abridged form): “1. A hollow container into which molten metal etc. is poured or soft material is pressed to harden in a required shape…” “2. Furry growth of fungi on things of animal or vegetable origin that lie for some time in moist warm air.” “3. Loose earth, upper soil of cultivated land, esp. when rich in organic matter.” The Oxford volume defines “mold” as “US variant of MOULD.”
There are quite a few examples like that - words that have one spelling in British usage and another in American. Others include “harbor/harbour,” “color/colour,” “aluminum/aluminium,” and “specialty/speciality.” (In the latter case, the Oxford volume lists both - without any nationalistic identity. The American one lists “speciality” as “Chiefly British.”)
Another distinction that trips some people up concerns the use of quotation marks. In American usage, the double quote (") is used to set off a direct quotation; the single quote (') sets off a quotation inside another quotation. The British do it the other way around. That one frequently confuses students - largely because so many books originating with British publishers get distributed in the U.S. under the labels of American firms - with no modification to the punctuation. (The quotations in the American editions of the Patrick O’Brian novels are punctuated in the British style. Those in the American editions of the Harry Potter books, on the other hand, are handled in the American style. I imagine the British editions of Harry Potter are different; presumably the American publisher concluded that, in view of the huge U.S. market, the expense of the change was justified.)
It probably would take an etymologist to sort all this out thoroughly. I think some of the distinctions may have originated relatively recently. When I was working on my book about the British Navy in the American Revolution, I had to read lots of letters and other documents written during that period. Eighteenth-century British naval officers sailed into and out of harbors on a regular basis, but I never encountered a reference to a harbour in any of those documents.
Interesting stuff - though hardly of earth-shaking importance. I never cease to be amazed at how adept people from non-English-speaking countries are at learning the English language. (The American public school system’s teaching of foreign languages is, by contrast, notoriously awful - as my own ineptitude demonstrates whenever I meet somebody from France or Germany.) The English language is a thing of great beauty, but it’s riddled with inconsistencies and irrationalities. I can’t imagine what it must be like to learn it as a second language.