Baire Ji,

Lightroom and Photoshop are not the same programs in my opinion. Their purposes are totally different. Lightroom is meant to be a workflow management, image magement and catalogueing software. Whereas Photoshop is for image editing and processing. While Lightroom allows you to do quite a bit of editing within itself, you will still need Photoshop when extensive editing is required, for example stitching a panorama or performing complex layer based editing.

Photoshop is intended for photographers and graphics designers as well, whereas, I believe Lightroom is primarily a tool for photographers. It does a superb job of catalogueing the pictures in a library, and if properly tagged, images can be retrieved in a flash.

I use both, not as a substitute of one another, but as complimentary parts.