The few parts from Apple's latest Time Capsule which are missing from the AirPort Extreme. | Source: iFixit
After dismantling the AirPort Extreme earlier on Wednesday, iFixit released images of a torn down Time Capsule.
As expected, the empty space seen in the Extreme is filled by a hard drive, in this case a 2TB Seagate Barracuda. Other than the HDD and its accompanying mounting and cabling hardware, the Time Capsule is nearly identical to the Extreme.
There is one difference on the control board, however, in a port to connect with the HDD. This space was left empty on the AirPort Extreme version.
HDD connector port.
iFixit gives the AirPort time capsule the same 8 out of 10 score as the Extreme, noting the two products are almost identical.