Among and Between are two commonly confused terms. Most people don’t make much distinction between the terms, but among grammarians, there is a very fine line.
Among should be used when discussing three or more or a group generally understood to be larger than two like a committee, educators, athletes, and politicians. Between should be used when referring to two; no more, no less.
So, you would say, “The decision was discussed among the committee members.” You would also say, “I had to decide between taking the red car or the blue car.”
What this means for you
To be honest, most people don’t care which one you use in speech. You will find the occasional grammar nazi that will slip into a coma when you use it wrong, but for most people, it just doesn’t matter that much. In writing, you should make the effort to use the correct term simply because it is more identifiable, more recognized, and more looked for. Much like Good vs. Well, using the correct term does not bother those who do not know better, but it does impress those who do. Might as well use it, right?