Difference between Photoshop Elements 11 and Lightroom 4?

I would highly recommend Lightroom. I now use it for 95% of my editing and Photoshop for the remaining.

Lightroom does not support editing layers.

Lightroom has a spot clone tool  which fixes many "blemishes" but I sometimes prefer the "spot healing" tool in Photoshop or Elements.

Lightroom can be setup to launch Elements when you select "edit" (vs Lighroom's "develop") but I think you'll find that you'll use Elements less and less.

If you do get Lightroom I suggest also buying the Lightroom 4 book by Martin Evening.

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A pixel is a terrible thing to waste.