According to Osho, withdrawing means becoming indifferent and aloof yet still oriented outward; introversion means shutting doors to life - no sun, wind, stars - so you merely vegetate, a kind of living corpse. 'Turning in' is a philosophical slogan, unnecessary because inner and outer are one organic whole. Life needs a balanced flow between both, not divisive labels like extrovert versus introvert.
Don’t split yourself into types; stay open to the world while being aware inside, because you are one whole.