There are 2 lounges in BRU - a separate Jet Airways lounge for Premiere and First class passengers - excellent lounge, I must add. Good views, F&B is great (they equate it to the airline F&B service, including champagne & stuff). There's also a kids play area, massager chairs, etc. You should have fun!

The other lounge is for JP Gold and Plat members, flying economy - this is a common lounge, and I think its the BA lounge that's shared by other airline passengers.

FYI, both lounges are on the same floor. After security, you go up one level. First comes the shared lounge, and then down the corridor is the Premier & FC lounge.