Apparently not:
Yes, you’re right. *Granum *and *gramma *in Latin; I should have looked a little more closely before posting.
In Afrikaans, koring means wheat, exclusively. Maize is mielie. Corn-on-the-cob is a mielie (pl. mielies) even in South African English. Maize meal is mielie meal or pap. But sweetcorn is canned maize kernels (which exclusively means the creamed variety)
The British author of the Falco books Lindsey Davis has a rant on this on her web site (scroll down to “A Gentle Corny Rant”). She took exception to an American reader suggesting “corn” shouldn’t be used in a book set in ancient Rome 
I used to get really confused about that (as an American). Books on Roman history are constantly referring to “corn” this and “corn” that, and since everybody knew that corn didn’t come to Europe until after the Spanish Conquest, I didn’t know what the heck they were talking about.
I agree with Hibernicus on the Irish perspective. Plus we put sweetcorn on pizza cos we’re rad.
In the US, field corn refers to all the varieties of corn that are used dry, including livestock feed and those treated to produce hominy, or ground up for polenta, cornmeal, or grits (my southerner husband and I have had many ‘discussions’ on the difference between polenta and grits), or processed for corn syrup, corn starch, and the zillion other things corn is made into.
Immature corn eaten as a vegetable, aka sweet corn, these days, refers to varieties known horticulturally as “super sweets” – corn that has a mutation that keeps the corn sugars from turning quickly to starch. So the tradition of starting your pot of water boiling and then rushing your fresh-picked corn to the kitchen has now died; these types have taken over the vegetable section of your grocer and will stay sweet for as long as you wish to keep them (until they get moldy). Became popular in the 1980’s. Regular old sweet corn was a mutation which was just sweeter than normal – it was selected I think by the Iroquois.
You can sort of look at it as, the US has a major native grain we call corn, and Britain has a major native grain they call corn. Then we both needed different names for other grains.
pleech. That stuff doesn’t taste like corn. When I was kid, we had butter and salt on our sweet corn, and it tasted like corn.
Modern sweet corn doesn’t have any flavour but suger. Putting butter and salt on it is like putting butter and salt on apple juice.
In AUS, cornflour is still, rarely, wheat starch. Since our supermarkets have reduced the number of lines they carry to less than half, most only carry one brand, and that brand is, more often than not, maize based. 30 years ago it was always wheat starch.
Starch is not, of course, flour. It tastes different for a start. It cooks different. Equally important, cornflour made from wheat may be gluten free: it doesn’t contain wheat protein except as a contaminant. It may be safe for celiacs even though it is derived from wheat.
In fact, the only reason I know that tradional cornflour is still available is because a celiac I know asked WTF was the thing with “cornflour” made out of wheat.
For cooking, wheat starch is interchangeable with maize starch. This because when they started making “cornstarch” from maize, they selected maize that had starch that matched wheat. Also, because maize naturally has a starch that is the same as wheat.
“Starch” is actually a mixture of two starches, and “cornstarch” will be the same as long as the balance is the same, were ever it comes from. Rice has a different balance, so rice-starch is not interchangeable with “cornstarch” for cooking.
Yes there are quite a few staunch advocates of the old type open pollinated sweet corn. You have to grow it yourself though. In the US, Johnny’s Selected Seeds is a good source.
Interesting to note that in Latvian, most any kind of bread is called… maize (pronounced “MY-zeh”). Rather different etymology, though.
I am not seeing any confusion or bother there. hibernicus is only saying that that Ireland is like America in using “corn” generally to mean maize. I was saying that is only Americans who get confused or bothered about other English speakers using the word to refer to other grains.