Lite-On LTD-166s and XJ-HD166s: are they the same drive?
I think so!
yes, they are
Is one OEM and the other retail?
Also, modded firmwares can be used interchangeably in either?
No, they are the very same drive!
I think that Lite-ON had some legal patent related issues! So they joined JVC and made JLMS (JVC and Lite-ON Manufacturing and Sales Limited). Than they started selling their LTD DVD-ROM drives as JLMS!