Typically, a camera's sensor resolution and stream resolution are the same. So a camera with a 3MP imager supports a 3MP stream max.
However, sometimes the actual stream resolution supported is significantly less than the imager resolution. Worse, some manufacturers try to obscure this to make their cameras look higher resolution, causing confusion and disappointment for users.
Panoramic cameras are the most common example of this problem. In this note, we explain the differences and the risks involved.