I have browsed through the forum and have done a couple of searches but have not found exactly what I am looking for. Sorry if this has been covered before I'm not sure if the terms I used for the search where even the right terms to search for.
Well here is my question. On some blu-rays and UHDs I see both Dolby Digital TrueHD Atmos and Dolby Digital Plus 7.1 with their respective Dolby digital 5.1 downmixes.
For example
Dolby Digital TrueHD Atmos
-Dolby Digital 5.1
Dolby Digital Plus 7.1
-Dolby Digital 5.1
Is there a difference between the two different 5.1 downmixes? Is one better to select than the other?