To ID Drongos species, the easiest is to look at its tail.
Greater Racquet-tailed Drongo have two long distinctive tail rackets. It absent or shorter in Lesser species
To differentiate it from Black Drongo, Bronze or Ashy species you have to look carefully at the feather colour and a beak.
Lesser Racquet-tailed Drongo (Dicrurus remifer) in glossed metallic blue, at Fraser's Hill @ Jelai Resort.
Greater Racquet-tailed Drongo (Dicrurus paradiseus)