Most composers have a distinct style that they use which comes through in whatever they write (even if they try not to). You can easily identify a show's composer by hearing these tendencies or styles they use. Almost all broadway composers have something about their compositional style that makes them unique -- but also makes a lot of their works sound similar.
You can tell when a piece is written by Sondheim, Lloyd Webber, Boublil/Schoenberg, Yazbeck, Kander, etc. In the golden age the music of Richard Rodgers, Cole Porter, and even George Gershwin sounded similar and was easily recognized as having their particular "sound".
Heck you can even go back to the classical period and earlier. Beethoven and Mozart had easily recognizable styles and tendencies of their own as well.
"You pile up enough tomorrows, and you'll find you are left with nothing but a lot of empty yesterdays. I don't know about you, but I'd like to make today worth remembering." --Harold Hill from The Music Man