I believe both the Touch and the Glo have 2 GB onboard storage, of which 1 GB is available for storing books (the rest is used by the device itself). Both can be expanded to 32 GB with a SD card (Touch) or micro SD card (Glo).
Touch specifications
Glo specifications
In my opinion, at £99, the Glo is worth the extra £20, because it has a built-in front-light.