Dear @Kasia.Patryniak,
The axis normal to the rotor plane is the axis of the shaft for rotor without teetering. Instead, the difference between AeroDyn output RtAeroFxh and ElastoDyn output RotThrust has been discussed several times on this forum, e.g., see the following forum topic: NREL 5-MW reference turbine - CP, CQ, CT Coefficients - #32 by Chenxu.Zhao.
Best regards,