Both models have 88 touch sensitive keys that look like piano keys but don't feel like weighted keys (because they are not).
The Casio sells for $499 and the Yamaha sells for over $600. Both have wooden stands. The Casio has stereo outputs, the Yamaha does not.
Sounds in both are similar in quality, the drum sounds are better on the Yamaha. The Casio has a lot more features including a digital programmable drawbar organ, a realistic leslie simulator which can be controlled by the modulation wheel, a programable synthesizer which means you can edit the sounds and store your creations, both have USB, both let you store songs you create on their internal sequencers on either a USB drive on the Yamaha or a SD card on the Casio.
Casio also allows you to load new styles, samples and drum sounds from their library directly into the keyboard.
The casio speakers are louder but both sound good.
The casio can handle two pedals the yamaha only one.
George Kaye
Kaye's Music Scene
Reseda, California