Lightroom's editing module - the Develop Module - uses Adobe Camera Raw or ACR.
ACR first appeared with Photoshop 7.0.1 in August of 2002.
ACR 3.0 first appeared with Photoshop CS 2 (Photoshop 9) in April 2005. (Photoshop 8 was named Photoshop CS - Creative Suite.)
Lightroom 1.0 started shipping in February of 2007 (about the time this thread was started), some 4.5 years after Photoshop 7 and the Lr Develop Module was ACR 3.0.
Photoshop CC 2017 is
Photoshop 18.
Both Photoshop CC 2017 (released Nov.2, 16) Camera Raw and Lightroom CC 2015 (Lightroom 6) use ACR 9.1 which was released in June of 2015.
Note too that Adobe Photoshop's Photography subscription includes
both Lr and Ps.
Because Lightroom's primary function is image database management, and Lr was designed to be a front end application to compliment, not replace, Photoshop.
Both Lightroom's Develop module, and Photoshop's Camera Raw have a lot less editing capability than Photoshop has.
Since both Lr and Ps use ACR it's easy to switch back and forth between the 2.
A better application for image database management, and as good or better for Raw file conversion is
Phase One's Media Pro.