The Momentus XT
is a true 1TB SATA hybrid drive, while the Black2
is a 120GB relatively low-performance mSATA SSD combined with a proprietary 1TB HDD in the same SATA enclosure. The Momentus XT is seen as a single 1TB volume by any system that supports standard HDDs and needs no special software to function, while the Black2 is only seen as a single 120GB volume by all systems, with the second 1TB volume only showing up on PCs where the proprietary companion software has been installed. In addition it cannot be connected externally via USB (to read or recover data using another system for example), and has other compatibility issues such as not being supported if the system uses an NVIDIA storage driver or if it is connected to the system via an ASMedia controller chipset.
For a high performance laptop drive I would recommend a full SSD or a true hybrid drive like the Momentus XT. Scott.