 L2 acquisition, however, does not share this similarity with late L1 acquisition, L2 learners being generally more successful than the latter.Additionally, child L2 and adult L2 learners differ greatly in the developmental paths they take and their ultimate attainment.The Fundamental Difference Hypothesis  refers to how linguistic methods of language acquisition applied in early childhood are not available for adult learners, which points to a fundamental difference in access to UG between child and adult learners.