There are no different specifications. LaCie (or anyone else for that matter) goes to manufacturer X, orders X amount of their X drive, then puts it in the nice enclosures and sells it with a one year warranty. The only thing that could remotely be different, and this is not always the case, the drive in the LaCie enclosure might have an OEM serial number to make sure the end user cannot circumvent the LaCie warranty and seek warranty from the drive manufacturer. But that usually only happens with big system manufacturers (Apple, Dell etc.) and not with external enclosure designers simply because their volumes are not that high to grant the changes.
Other than that, the drive would be identical to the ones sold as retail kits.
If you use a PC, download PCWizard from here:
http://www.cpuid.com/pcwizard.php
It will tell you all that there ever is about your PC, including the manufacturer of each of your HDs with their serial numbers. Just connect your external drives and check to see what's inside.