If you turn your apple retina display to 1080p mode, then I would think it's not that good when there's a 1:1 correspondence between physical pixels and pixel data. However when the size stays the same, I wouldn't expect much difference.
A 32 inch 4k display downsampled to 1080p, well... :)
A down-sampled image has less noise than an image in its native resolution. You can experiment on your own monitors if you don't believe the theory, just remember to use font smoothing for non-native resolutions. You can also ask about it on the appropriate stack exchange, it is a frequent topic of confusion.
This is one of the advantages of shooting at a higher resolution than the intended target delivery resolution. When downscaling an image, the noise gets 'averaged' out of the image. For HD 1920x10280, a 2.7K resolution was a good choice before having to jump all the way to 4K. There's other technical reasons as well for shooting larger than intended use, but just re-enforcing the 'noise removal' process of downscaling an image.
A 32 inch 4k display downsampled to 1080p, well... :)