Does the antenna length differ between transmitter and receiver?
With the small differences between the two antennas, and the fact that they are both coiled -- there is little difference substituting one for the other would be. 

An ideal antenna has no coil, but then it would have to be over a meter long at 433MHz. By adding inductance (the coil), the antenna can be resonant near 433MHz without needing the length. The sacrifice is sensitivity, but since both antennas are coiled, there's little you gain from one over the other.