The magnetic structure of the hexagonal stannide NdCuSn has been studied by neutron powder diffraction at low temperature. Magnetic ordering occurs below ~10 K and is associated with two magnetic wave vectors, q1 = (0,3/8,0) and q2 = (1/2,0,0) or (0,1/2,0). The q1 vector is attributed to a majority fraction (>90%) of the NdCuSn phase having an ordered Cu/Sn sublattice (non-centrosymmetric NdPtSb type structure, space group P63mc). It can be described as originating from a transverse sine wave modulated arrangement of spins oriented || c with a maximum moment value of 2.2 µB/Nd atom, or alternatively by an antiphase domain structure having two amplitudes. The q2 vector is attributed to a minority fraction (<10%) of the NdCuSn phase having a disordered Cu/Sn sublattice (centrosymmetric CaIn2 type structure, space group P63/mmc). It has a simple antiferromagnetic +- moment arrangement along a or b and the moments are oriented || c with a refined value of about 1.2 µB.