An action is something you do (“Take the job and move”). A need is what that action is meant to give you (“Career growth”). In the method, actions are sometimes called requirements.
Conflicts happen between actions, not needs. Both needs are usually valid, which is why a good solution meets both.
Test it: “In order to get [need], I must [action].” If the sentence reads naturally, you have them the right way round.
Common mistake
Writing another action as the need, such as “Move to London”. Ask “why does that matter to me?” until you reach the underlying need.