according to the US Food & Agraculture, an administrative body that sets standards for US foodstuff:
Jelly is made from clear fruit juice, with sugar and pectin, (there are percentages/ratios of sugar to fruit juice that must be met in order to be called jelly--(sugar free stuff for example is a fruit spread))

Jam is made from fruit juice and pureed fruit bits (at least 10%pureed fruit) the fruit does not have to be intact and recognizable (ie, a puree of fruit and juice) --same deal with specific ratios of sugar to fruit apply--with there always being more fruit by weight than sugar)

preserves are made from fruit and juice(notice--fruit comes first, not juice). the fruit can be cut up, but peices of intact fruit must be still visible, plus sugar and pectin.

(i don't know if there are standards for marmalades, or curds (like lemon curd))

if a product meets the government standard, it doesn't have to list its ingredients on the label. (it can but it doesn't have to)
IF it doesn't meet the standard, IT MUST List all ingredients, in order by weight.. (heaviest/greatest quanity first--

which mades canned chili makers to use 3 types of beans in their chili--so Beef is #1 ingredient, and Bean A, BeanB, Bean C follow (along with other ingredients).. but in reality, the chili is more beans than beef.

there are many foods with 'standards' established, (peanut butter, for one, ketchup, mustard, mayonaise, ice cream, and so on..)

and here, in US, we call gelatins 'Jell-o'--after the biggest brand of mixes for making them.

blancmange is pretty rare,--i have made it.. but its not at all common.

Bavarian creams used to be fad.. they are like a blancmange that is made with added whipped cream. and are sometimes called souffles, (but unlike a real souffle, they are not cooked) and Bavarian creams came in all sorts of flavors, fruit, chocolate and even coffee flavor.

of troy, who knows her sweets and desserts!