The new GIRM translation contains more than a thousand changes from the one that has been in force since 2002. Most notoriously, the word song is changed to chant – and chant clearly distinguished from hymn (see 86) – and new conditions are added for the option not to sing the actual proper of the Mass: Such a replacement chant must be “suited to the sacred action, the day, or the time of year.”
Paul Ford has very helpfully marked up a huge file to compare the versions side by side, and highlight the portions that apply to music in red. Here is the link.