According to Digital Photography Review, which has had a chance to preview the new camera, the primary difference between the T3i and T2i is that the T3i has an articulated LCD, which means that some of the controls on the back of the camera had to be repositioned, and the camera is slightly deeper and heavier than the T2i.
The T3i uses the same sensor and processor as the T2i, so its ISO range and video performance are identical to the T2i. However, EOSHD.com reports that the T3i has a 3X and 10X crop mode; the 3X mode is the most interesting, because it crops the image to 1920x1080, which should decrease the imager's rolling shutter problems. (Update: Commenters to EOSHD.com are suggesting that the 3X and 10X modes are actually digital zooms, not crop modes, which would result in a much lower-quality image.) The other primary functional changes to the T3i are "beginner-friendly" new features, including:
- Basic+, which simplifies adjustments to exposure and scene mode parameters.
- Scene Intelligent Auto mode, which automatically selects exposure and scene mode, and adjusts color balance, based on whatever the camera is pointed at.
- Video Snapshot mode, which allows a sequence of 2, 4 or 8 second long video clips to be strong together without requiring video editing.