Akash, you should really stop posting those links. They are wrong, and they are misleading. I have no idea why Scott Kelby doesn't know better; he really should.
So to be perfectly clear:
- there is no reason whatsoever Lightroom and Photoshop color settings need to "match".
- the Lightroom native color space is not ProPhoto. That's just an arbitrary export to Photoshop default, because there has to be some default.
- Lightroom's native color space is a custom color space with linear tone response curve. It does not exist, nor has it any equivalent, outside Lightroom.
- as per the above, Lightroom and Photoshop color spaces cannot ever match, and nor should they.
- color managed applications like Lr and PS are color managed, and will display correctly whatever color space is used.