Between is traditionally associated with two people or things, although it can also be used for more than two when referring to distinct individuals or relationships.
- The agreement was between Kenya and Tanzania.
- She divided the money between the two children.
- There is a strong relationship between the three organisations.
Among means surrounded by or included within a group.
- He was standing among the crowd.
- She felt comfortable among friends.
- The decision was discussed among the team members.
Simple guide
Think between = individual relationships and among = within a group.