From my understanding, you would need to first have a patent to protect your ideas. An NDA protects you from other people that get involved in the project. You may need to have both to fully protect your ideas, especially when involving a third party. A patent, as described above, will ensure that no one can replicate your ideas. An NDA ensures that no one that knows of it in more detail will go and sell your idea or even share the information in a casual setting. However, an NDA requires that the person signing it is fully trusted.