Same thing. http://learnersdictionary.com/definition/each%20other http://learnersdictionary.com/definition/one%20another

You can use each other and one another to show that each person in a group of two or more people does something to the others. There is very little difference between each other and one another and you can normally use them in the same places. Each other is more common than one another.

We use the reciprocal pronouns each other and one another when two or more people do the same thing. Traditionally, each other refers to two people and one another refers to more than two people, but this distinction is disappearing in modern English. source: https://learnenglish.britishcouncil.org/en/english-grammar/pronouns/reciprocal-pronouns-each-other-and-one-another