I followed this up a bit, as I was also pointed to the new, quieter milk foam system in a video. As far as I have seen, the EP5441/50 is the same as the EP5447/90, except that the 5441 is black at the front and the 5447 is silver. See the press release: https://www.philips.ch/c-dam...

And what is the difference between the two models except 100.- more?

Without being able to answer the question directly, as I don't know if I have the newer version. The milk system is not the loudest part of the machine anyway. With a fully automatic machine, it's usually the grinder.