You can go through and process images on an individual level much faster in LR than you can PS. LR also automatically organizes your files, and applies any dating, numerical reference, or name you give them during import or export.
PS Camera Raw and Lightroom's Develop Module use the same edit rendering engine, sliders, and panels - Adobe Camera Raw (ACR). Consequently, using a good Bridge/ACR workflow instead of Lightroom it is possible to process images on an individual level just about as fast with Photoshop CS.
Note: There are 3 Process Versions of ACR.
http://help.adobe.com/en_US/lightroom/using/WS2bacbdf8d487e58240e1c02a1341ed8e630-8000.html.
Lightroom does not automatically organize your files. The user still has to tell Lightroom what files go in which Lightroom virtual catalog, collection. or folder. The only files Lightroom knows about are the files the user tells Lightroom about by uploading/importing them using Lightroom's Library Module. Actually none of your files are
in Lightroom. Lightroom just keeps track of where your files are in your computer's memory. If you move a file Lightroom knows about using an application other than Lightroom, like your computer system file mangement capability, Lightroom will no longer know where that file is.
Lightroom is based on 2 software engines - it's image catalog database management engine, and it's Raw image data file rendering engine.
PS Bridge and a lot of other file management applications "applies any dating, numerical reference, or name you give them during import or export". Both Bridge and Lightroom allow adding keywords, rating images, completing IPTC data fields, etc, and both have templates allowing a lot of that to be done using templates during image ingestion.
The difference is that Bridge is a browser and Lightroom is a database manager. Because Lightroom is a database manager,
IF the user has used good digital asset management practices while building a catalog, collection, folder, Lightroom can search the database of images more efficiently than a file management (browser) application can.
I often recommend these books be kept at hand for reference:
The DAM Book: Digital Asset Management for Photographers
Adobe Photoshop Lightroom 4 Book: The Complete Guide for Photographers
The Digital Negative: Raw Image Processing in Lightroom, Camera Raw, and Photoshop
Real World Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom (2nd Edition)
Adobe Photoshop CS6 for Photographers: A professional image editor's guide to the creative use of Photoshop for the Macintosh and PC