Above are some stock shots of both cases. The only major internal difference between the two is the design of the hard drive bays. The 800D ships with a side-mounted fan and a preinstalled backplate for the four hot-swap drives. The 700D's hard drive fan is mounted horizontally instead of vertically, and all of the bays are internal.
Here is the 700D's hard drive bay, with drives installed and not. There's ample clearance for airflow between each drive and the installed fans should prevent the HDD bays from becoming a hot spot.
These are shots of the system's back ports for cable routing and removable rear plate for CPU cooler adjustment. Corsair cut enough holes through the case to allow for almost any type of cable on the market, with multiple routing points available for various cable lengths. If you obsess over cable ties, one of the Obsidian cases may be right for you—it's possible to shift virtually every cable in the system to route behind the motherboard.
The CPU plate is cut wide enough to allow for nearly any motherboard design and grants easy access to the mounting hardware. This feature comes in very handy if you're trying to diagnose a heat problem; instead of pushing and tugging on the heatsink mounts, you can check behind the case.