We establish the equality of the specialization $P_\lambda(x;q,0)$ of the Macdonald
polynomial at $t=0$ with the graded character $X_\lambda(x;q)$ of a tensor product of
"single-column" Kirillov-Reshetikhin (KR) modules for untwisted affine Lie algebras. This
is achieved by constructing two uniform combinatorial models for the crystals associated
with the mentioned tensor products: the quantum alcove model (which is naturally associated
to Macdonald polynomials), and the quantum Lakshmibai-Seshadri path model. We provide an
explicit affine crystal isomorphism between the two models, and realize the energy function
in both models. In particular, this gives the first proof of the positivity of the $t = 0$
limit of the symmetric Macdonald polynomial in the untwisted and non-simply-laced cases,
when it is expressed as a linear combination of the irreducible characters for a
finite-dimensional simple Lie subalgebra, as well as a representation-theoretic meaning of
the coefficients in this expression in terms of degree functions.