vous vous intéressez = you are interested. The verb is "s'intéresser" (to interest oneself). The second "vous" is a pronoun. Because it's conjugated in the present tense, it's like a reccuring thing in your life (habbit) so it's perceived as something your actively do all the time. vous êtes intéressés = you are interested. Here "intéressé" is like a quality (how are you ? interested).

Sorry, I can't see a real difference in the meaning... So, I will just sumarize the grammatical difference. 1. s'intéresser à ~ Verbe pronominal ex : Lenna s'intéresse à la diététique ex : Je m'intéresse à la diététique 2. intéresser SUBJECT don't accomplish any action, but has a proprety/attribute: it "attracts" the OBJECT (people / group / compagny / etc.). ex : La diététique intéresse Lenna. ex : La diététique m'intéresse. (m' = me = moi-object) 3. être intéressé par ~ Passive voice of n2. Passive voice means usually: OBJECT becomes SUBJECT ex : Lenna est intéressée par la diététique ex : Je suis intéressée par la diététique The tricky thing is that in the structure 1 and 2, if you talk about yourself, you will get a "me" in front of the verb. Case 1: verbe pronominal Case 2: pronoun (object)