1. Lightroom is built for photographers.
While Photoshop has everything you might need, it also has a ton of features you don’t need, like 3D rendering, video tools, and vector graphics. These extra features mean more disk space (about 1GB for Photoshop compared with about 100MB for Lightroom).
2. Lighter processing requirements.
Lightroom runs fine on a laptop or lower end machine. True, it will run better on a faster machine with more memory, but I have no trouble at all using Lightroom on the road with my laptop – a situation that has Photoshop plodding along.
3. Excellent image management.
Lightroom import can make duplicate copies of your images, one for the catalog, and another as a backup, even doing so in different formats (say raw for the catalog and DNG for your archival copy). Applying keywords and metadata to your images on import is easy, and you can apply processing presets as well.
4. Strong searching and organizing.
Because the Lightroom catalog is a database file, it’s easy to find all your images, whether by keyword or metadata such as camera type, ISO, etc. Lightroom also lets you create collections that make it easy to group similar images together. The Smart Collection will automatically add images to the collection based on criteria like keywords.
5. Logical Workflow.
Lightroom is organized into modules – Library, Develop, Web, Slideshow, and Print. You only see the features that make sense for that module, making Lightroom both quicker to learn, and faster in performance.
6. Excellent conversions.
Lightroom uses the same raw processing routines as Adobe Camera Raw, meaning most digital cameras are supported, and the conversion options have been through a number of improvement cycles.
7. Non-destructive workflow.
No edit in Lightroom will permanently modify the original image. Regardless of file type – JPG, TIFF, DNG, RAW, PSD, all editing in Lightroom is non-destructive. Changes are stored in either an external XMP file, or in the Lightroom catalog file as a list of adjustments. You can go back at any time and undo or modify those adjustments.