Yes, there is definitely a vast difference between initiated and non-initiated. One who is initiated is authorized, and one who is not initiated is not authorized. Just like, for example, Pradyumna is attending class in Sanskrit in a college, he is given chance to learn Sanskrit, but he is not equal with the regular students. One who becomes initiated is channelized to the authorities in the disciplic succession.
One who isn’t initiated may chant Hare Krishna (and should certainly be encouraged to do so) and serve in his own way, and gradually by doing so he may want to be initiated. But otherwise he may fall away from following the rules and regulations.
Letter to Satsvarupa Das – November 14, 1968