It usually helps to include a full sentence. It's sometimes hard to understand without some context. I will try to explain using the language I am learning, which happens to be your native language :)
"'All singers" means all singers. 모든 가수 ?? e.g. All singers eat macaroni. 모든 가수 는 마카로니를 먹어요.??
"All the singers" means all of singers mentioned or referenced before. All the singers eat macaroni. 가수들은 다 마카로니를 먹어요.??