The answer, is very well.
In the following images you can see a comparison of both outputs to a 4k/HDR display. Image sharpness is very close, color is almost as vibrant, and contrast is virtually indistinguishable.
Where we can find slight differences is in the black levels. The 4k Blu-ray appears to have richer blacks and more definition in the edges. In other words, the 4k Blu-ray has a bit more punch.
Keep in mind this was not a live DirecTV channel but rather an on-demand viewing (live broadcasts are still generally 720p or 1080i). The movie was found using Search and downloaded on the DTV Genie DVR. It took some time to start (given the size of the stream) and we encountered many “buffering” delays. But, as you can see the results are very good.
The biggest difference between DirecTV and the 4k Blu-ray presentation of Angels & Demons can be found in the audio formats. The UHD BD offers immersive Dolby Atmos. So, if you’re an audiophile there is no reason to watch the DirecTV version of Angels & Demons if you have the Ultra HD Blu-ray on hand.
How are DirecTV and several other providers delivering high quality 4k content? This movie, along with hundreds of others, are available through a partnership with Movies Anywhere. Look for the little “M” icon next to titles that you search for on your set-top box.