The Ultra Fit A has a cutout on back to display the Apple logo. The Ultra Fit and Ultra Fit S do not. And the Ultra Fit and Ultra Fit A are a soft matte finish all over, while the Ultra Fit S has a brushed finish in its midsection.
The Ultra Hybrid is a bumper, with back protection. (1) It's made of TPU (for anti-shock) vs. the all polycarbonate (for anti-slip) Ultra Fit/A/S.
(2) It also has power and volume buttons overlaying Apple's, which the Ultra Fits do not. (3) Lastly, it covers all four sides, whereas the Ultra Fits cover the left and right sides and wrap around the four corners, leaving the top and bottom exposed (which is good if you want to connect some models of headphones or adapters that require more space there).
They're all properly designed for the 5/5S flash, including the black around that cutout (you don't want to buy a case that doesn't have a black rim there).
IMO Spigen's slim cases are better made/more durable than other third-party cases (of which I've bought aplenty). I love mine!