Traditional grammarians often say that “each other" is used to refer to two people or objects. On the other hand, “one another" is used when the number is more than two. Nevertheless, this strict rule is not maintained in present day English. Modern grammarians like Swan remark that there is little or no difference of meaning between the two expressions. The two terms are thus used in modern English almost interchangeably. Still if we have to differentiate between the two terms, it can be said that we prefer “one another" when we are making very general statements, and not talking about particular people.
1. They waited for almost an hour without talking to each other / one another.
(Both forms can be used here)
2. People talked to one another about the recent price hike.
(“Each other" can be used and that will also be grammatically correct, but “one another" seems to be a better choice")