You got front and rear derailleurs. The front is connected with the crankset. The rear is connected to the casette. Often they are in the same group (gruppo) f.ex Dura Ace, 600, Super Record and usually by the same maker; Shimano, Campagnolo etc. All together refered to as components. On older bikes there could be a mix of different stuff, but often from the same country (components that is). Brakes, rims and bars could be an entirely different maker. Lugs can be an area of interest to many; what making and what year. Yours are Nervex. And the seat; yours look on the average side... I gatherad there should have been a brownish Kashimax.

Yours could do with a little tidying up! You´ve got a hard to come by gem there! Clean it thoroughly, look over its components and its functions. Kiss the bar tape and seat goodbye?