Srila Bhaktivinoda Thakura explains the Gaura-gopala mantra in his Amrta-pravaha-bhasya. Worshipers of Sri Gaurasundara accept the four syllables gau-ra-an-ga as the Gaura mantra, but pure worshipers of Radha and Krsna accept the four syllables ra-dha krs-na as the Gaura-gopala mantra. However, Vaisnavas consider Sri Caitanya Mahaprabhu nondifferent from Radha-Krsna (sri-krsna-caitanya radha-krsna nahe anya). Therefore one who chants the mantra Gauranga and one who chants the names of Radha and Krsna are on the same level.