In two-dimensional space a subtle point that for the case of both space–space and momentum–momentum non-commuting, different from the case of only space–space non-commuting, the deformed Heisenberg–Weyl algebra in non-commutative space is not completely equivalent to the undeformed Heisenberg–Weyl algebra in commutative space is clarified. It follows that there is no well-defined procedure to construct the deformed position–position coherent state or the deformed momentum–momentum coherent state from the undeformed position–momentum coherent state. Identifications of the deformed position–position and deformed momentum–momentum coherent states with the lowest energy states of a cold Rydberg atom in special conditions and a free particle, respectively, are demonstrated.