A panorama is a 360° image. We have panorama support in the Mapillary viewer (use your mouse to pan around).
For an image to function as a panorama on Mapillary, it must be equirectangular (2:1 aspect ratio) or contain GPano Photo Sphere Metadata.
If the resolution doesn't correspond to a full 360x180 panorama, Mapillary will treat this like all other images. With some cameras, it's just a matter of a few pixels and you might be able to fix it by adding some padding to the images before you upload. (Note that this also works the other way: if your regular image is so wide that it corresponds to the 2:1 ratio, it will be rendered as a panorama on our platform.)
The Mapillary mobile apps don't capture stitched panoramas. You can still get a panoramic view by just capturing a sequence of photos with lots of overlap. Once uploaded, you can use navigation arrows to "look around" with smooth transitions that enable a nice 360° view of the surrounding, even though the images have not been actually stitched together.