I am confused about the difference between a Degree and a Concentration; also, what does the Brown diploma actually say?
A Bachelor's degree is awarded at the conclusion of your undergraduate years at Brown. It will appear on the diploma as either a "Baccalaureato in Artibus" (AB) or a "Baccalaureato in Scientia" (ScB) degree. The name of the degree appears in English on your transcript.
A concentration is the program, or focus of the degree, in which you are registered, with various requirements that are known and delineated on your concentration forms, which have been signed by your advisor.
In four years (8 semesters-worth of tuition enrollment) at Brown, you may be able to complete more than one concentration program, but you will still receive one formal degree (the Bachelor's degree) in that time frame.
Your diploma does not have the name of your concentration program on it*, but your transcript DOES.
Your diploma will have your Name, your Degree, and the signature of the President of Brown (and, a few other items in Latin as well).
* If you complete Honors in your concentration, this information will be inscribed on your diploma (e.g., "Honors in Biology") in Latin, e.g. "cum honoribus in Biologia." The fact that you complete your concentration with honors will also appear, in English, on your transcript, e.g., "Biology - HONORS."
* If you complete more than one formal concentration program within the eight semesters, these will all be denoted on your official transcript, even if one is an "AB" program and the other an "ScB" program.