Photosynth.net hosts six different types of imagery at this point in time:
1: Original photosynths (multiple photos of something or somewhere taken with/from different camera positions, angles, zooms, orientations, or models - totally free-form against the backdrop of a 3D point cloud of the scene observed in the photos)
These can only be created and uploaded with the original Photosynth desktop application for Windows.
2: Spherical/stitched panoramas (multiple photos taken from exactly the same position [altitude, latitude, longitude], merged + blended onto the inside of a sphere/cube)
These traditional panoramas can be created using Microsoft ICE, Adobe Photoshop for Windows, Windows 8.1's Camera app, or Photosynth's mobile apps for WinPhone + iOS