Catholicism allowed for polyphonic music, where the words (in latin) were layered to produce very beautiful music. An extreme example is Thomas Tallis's Spem in Alium that has 8 choirs of 5 parts each:
https://www.youtube.com/watch?v=iT-ZAAi4UQQ
However Protestantism required the words to be in English and sung without polyphony - so that they could be understood by all. For example another work of Tallis's:
https://www.youtube.com/watch?v=R4fHU0Nales
Byrd in particular wrote a lot of works in the Catholic idiom that he had to hide, for writing such music could have got him killed.
https://www.catholiceducation.org/en/culture/music/william-b...