Here in Northwest Yearly Meeting you'll sometimes hear people describe the Friends' peculiar stances on things as "distinctives." I thought this was normal until I was speaking to Friends in Boston and someone told me they knew to which branch of Friends I belonged because I referred to the Friends testimonies as "distinctives."
In meeting for worship the other day, Paul Anderson spoke about the testimony of equality, and said something really helpful regarding the meaning of "testimonies" and "distinctives." (You can find that message on our meeting's podcast here.) He said that the testimonies are all Christian testimonies--meaning they are found in the Bible (although one can practice them without being "Christian"). Testimonies are for all time. They are things that are a good idea for all people, everywhere. These are things like equality of all people, living peaceably and doing intentional reconciliation work as needed, fostering community, etc.
"Distinctives," on the other hand, are the particular way we each (or each generation) feel led to live these things out. So where the testimony of good stewardship, for example, might be a good idea for all times and all people, the "distinctive" of Friends today might be aimed toward stewardship of the environment, because that is the area with which our particular time and place struggles. Likewise, the testimony of equality is important for everyone, but during the nineteenth century in the United States, Friends lived this out distinctly by advocating for abolition of slavery and the right of women to vote, among other things. I really liked this way of defining these two terms and I thought it was helpful, so I thought I'd pass it along.