I never learned to ride a bike. It is my deepest shame.
Two main differences:
The drivetrain components on the CX are considerably better quality than those on the Uno. This may not be too noticable when the bikes are new, but the CX components will take a lot longer before they feel worn out and will be easier to keep adjusted. Also the shift levers on the Uno are a different style that has a 'downshift' lever that can only be reached from certain positions on the handlebar, while the CX has a better design that is easier to use. Also the CX has 10 cogs on the rear (20 speed total), which is the modern standard, compared to the Uno's 8 speed cassette (16 speed total).
Also the frame on the CX is 'butted' chrome-moly steel (tube walls are thinner in the middle and thicker at the ends), which is lighter and will probably give a better ride than the 'plain gauge' chrome-moly steel on the Uno.
I would consider the CX to be worth $250 more than the CX. They both look like excellent bikes, though.