Which is best for you?
Both is the easy answer. What are the real world differences? Well lightroom does a few things to a lot of images while photoshop does a lot of things to a few images.
Lightroom is really designed to manage and edit your images, but it only has limited editing, theres no layers, no cutting and pasting, limited cloning and healing (poor IMHO) Limited localised ajustment. But what it does have is good colour and exposure editing, and it does batches of images well, something photoshop with all it's amazing features still manages to make difficult.
For me I need both, I use Lightroom for large numbers of images, say a wedding where most of whats needed is a quick tweek to colour exposure, and Photoshop for the tricky stuff like cloning or removing objects from the background, swopping eyes, stuff like that, things Lightroom simply can't do.
