When watching the film "Neredesin Firuze" the other day, I noticed that "ama" was used pretty consistently for the English conjunction "but" and I am curious what the difference is between "ama" and "fakat"? The Routledge grammar says they mean the same (although it gives an example of "ama" used at the end of a sentence).

Is there a difference or are they interchangeable? Might "ama" have a different stylistic color or belong to a different register or dialect? In other words, were the characters in the film more likely to have used "ama" than "fakat"?

Thank you for any responses.

Yes they are interchangeable and have the same meaning. We had three different words for the same term: ama, fakat, lakin. With time the third one is omitted from usage. Fakat will be also omited in a few years. It has become already very uncommon.