A) We use BETWEEN for two things which are clearly separated. We use AMONG for things which are not clearly separated because they are part of a group or crowd or mass of objects. AMONG and AMONGST are the same thing; e.g.

i) Our house is between the park and the market. (the park is on one side and the market on the other, means clearly separated)
ii) The hut was hidden among the trees. (surrounded by trees, means not clearly separated)

NOTE-I: However if we see things individually/separately we use BETWEEN even when the number of people/things is more than two; e.g.

i) Switzerland lies between France, Germany, America and Italy. [More than two things, but you can’t use AMONG here as all these four countries are being seen individually; not as a part of group.]
ii) He stood among all his friends in the room. [You can’t use BETWEEN here as FRIENDS are not being seen individually.]
iii) There is a treaty between these four countries.

NOTE-II: We do not use AMONG even if the number of people/things is more than two, when the preceding verb/noun/adjective requires a different preposition. In such a case we use that preposition (not AMONG); e.g.

INCORRECT: There is much fear among the children.
CORRECT: There is much fear in the children.

INCORRECT: He is very popular among the people of Delhi.
CORRECT: He is very popular with the people of Delhi.

NOTE-III: To introduce a prepositional phrase which contains two singular or plural noun phrases, we use BETWEEN (not AMONG) even when the number of people/things is more than two; e.g.

I didn’t see any difference between the real rings and the artificial rings.

B) To talk about something done to, or done by a group/groups of people/things, we use either BETWEEN or AMONG, e.g.

The money is to be divided between the towns in the area.
= The money is to be divided among the towns in the area.

The prize will be shared between the first six finishers in the race.
= The prize will be shared among the first six finishers in the race.

NOTE: But, when we specify the individual members of the group using singular nouns we use BETWEEN; not AMONG; e.g.

The money is to be divided between Ram, Mohan and Sohan. (You can’t use AMONG here.)

For more chapters/topics on English Grammar read the following book authored by me.

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For English Practice Sets on various topics read the following book authored by me.

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