For recreational depths and time, the different models produce reasonably similar results-- the RGBM, for instance, closely tracks the U.S. Navy table within recreational depths and times. If you wish to understand the intricacies of each model, you'll need to do some fairly heavy reading, especially for bubble models.
Mares uses its proprietary blend of the Reduced Gradient Bubble Model (RGBM). Suunto uses its own version of the RGBM. Aeris essentially "looks up" the information from the PADI/DSAT RDP database. Scubapro/Uwatec, TUSA, and DiveRite use the Buhlmann model, ZHL-8 or ZHL-16 depending on the computer.
Mares uses its proprietary blend of the Reduced Gradient Bubble Model (RGBM). Suunto uses its own version of the RGBM. Aeris essentially "looks up" the information from the PADI/DSAT RDP database. Scubapro/Uwatec, TUSA, and DiveRite use the Buhlmann model, ZHL-8 or ZHL-16 depending on the computer.