The "Bamboo Fun" was Wacom's bare-bones, entry-level, dirt-cheap, option. It was the least robust of any tablet. Wacom appears to have discontinued that model or anything like it.
The CTH-680S series are Bamboo tablets. Just not the "Fun" model. They are more in line with the standard "Bamboo" and the "Bamboo Create" tablets. They are slightly better than the Bamboo Fun was, but not a great deal better. They merely renamed the "Bamboo" line to "Intuos" and the CTH-680S series appears to be specifically non-American. Not sure why they use the number/letter model rather than the "Intuos" name.
This is the CTH-680S-DEIT (Intuos Pen & Tablet) and This is the CTH-680S-S (Intuos Manga)
These are still entry level tablets - and, in fact, they are the Bamboo tablets. You will gain a bit of pressure sensitivity and features with these tablets, but you won't gain a great deal. Technically, yes, these would be upgrades from the "Bamboo Fun" but not drastic upgrades.
The next logical step up from these is the Intuos Pro.
Other than the dramatic price difference, the Intuos Pro offers double the pressure sensitivity, higher LPI resolution, side buttons on the stylus, expression buttons on the tablet, ergonomics (tilt, rotation, etc) and many more features.
Then the next step above the Intuos Pro would be a Cintiq. The Cintiq is basically an intuos Pro built into a monitor. You connect it to a system just like you would connect a monitor, then draw on the screen with the stylus.