1) It did NOT happen on approach, They were not even over NZ let alone Auckland so what happened 500+ miles away is not related to Auckland windshear.
2) 50' is not a large drop and doesn't require a steep dive when flying at altitude to put people on the Ceiling, Just ask those onboard QF72 back in the mid 2000's, that was only a max of 8.4 degree sudden downward pitch.
3) For passenger no there is NOT a huge difference, a sudden attitude change exactly fits what passengers have described, as in like hitting a speed bump and both would appear similar for a passengers view point.