This kind of pixellation can happen if you export jpgs with a low quality setting.
Try setting quality to 80, and see if that improves the image.
Jpg uses lossy compression, and you have to find the balance between file size and quality.
Low quality = small file, high quality = bigger file.
Photoshop and LR should visually match color, if not, you've got a color settings issue, probably with Photoshop. Check your color settings. Make sure the Desaturate check box is off too. Windows viewer may not be color managed, don't even try examining it, stick with Photoshop. Export the data in 16-bit. If you see banding, it's in the display path, not in the image data.
Thank you so much! I didn't even notice the setting; it was defaulted to 60. I set it to 100 and voila! Thanks again!
So, after exporting from Lightroom to 100 quality, I can still see a little bit of banding, albeit not as bad! It's a good start. Can you please elaborate on Desaturate checkbox, and exporting 16-bit? Not sure what you mean by exporting....exporting in LR and PS? Thanks!