According to the FCC filing for the Motorola DROID RAZR HD, the device will have a 2530mAh battery which would seem to be large enough not to require a "MAXX" variant of the phone. Either the speculation is all wrong and there won't be a Motorola DROID RAZR MAXX HD or else there will be a variant with a larger capacity battery greater than 3300mAh.
Assuming that there will be a Motorola DROID RAZR MAXX HD, it should match the specs on the DROID RAZR HD except with the larger battery and a slightly thicker footprint. The latest speculation calls for both devices to have a display with resolution of 720 x 1280, a dual-core 1.5GHz Qualcomm Snapdragon S4 under the hood (most likely the MSM8960) and Android 4.0.4 installed out of the box.
Considering that an October launch would lead the new handsets right into competition with the next iteration of the Apple iPhone, you might want to start shaking that salt now.
source: HotHardware via Phandroid