  We present a comparison of the noncommutative field theories built using two
different star products: Moyal and Wick-Voros (or normally ordered). For the
latter we discuss both the classical and the quantum field theory in the
quartic potential case, and calculate the Green's functions up to one loop, for
the two and four points cases. We compare the two theories in the context of
the noncommutative geometry determined by a Drinfeld twist, and the comparison
is made at the level of Green's functions and S-matrix. We find that while the
Green's functions are different for the two theories, the S-matrix is the same
in both cases, and is different from the commutative case.
