Even if I can see why either should or should not be used in a particular sentence, I do not understand the actual difference between amid and among. Can anybody tell me how these two words differ ?
Among and amid are two prepositions with similar meanings but different usage.
Among means "in the midst of", "surrounded by", "by or through the aggregate of", "in the number or class of", etc. (MW).
Amid means "in or into the middle of", "surrounded by", "during", "with the accompaniment of", or "against the background of" (MW).
The two prepositions, however, are used with different types of nouns.
Among is used with plural, countable nouns, like dogs, tables, or books.
- I like The Cat in the Hat, among other books.
- He is a genius among men.
- There were several roses among the flowers I gave her.
Amid is used with uncountable or mass nouns, like rain, happiness, or darkness.
The treetops were visible amid the darkness.
They prospered amid a time of peace.
They continued to work, amid concerns that their efforts were misplaced.
Differencebetween.com provides a very clear explanation of the difference in usage, and offers an extensive selection of sample sentences.
Lexico offers a good review of countable vs uncountable nouns.
While the guidelines for usage are fairly straightforward, the distinction, like so many things in language, is not 100% writ in stone. This is because the two words are somewhat synonymous. The fact that many nouns (like "truth") can be used in both countable and uncountable forms can also complicate the choice.
As an illustration of the difficulty of drawing an absolute distinction, one of the sample sentences provided by Cambridge includes the words "The town sits amid gentle hills". It would be difficult to argue that among wouldn't work here just as well.