This is really pathetic. As I thought, the differences between these lines are cosmetic and exist purely for marketing purposes.
I kinda get why there is a luxury model because it has the chrome bits and some people like that BS. Kinda like the C-class sport model and the classic MB grille version. However, I think it's still tacky and why do we need a sport line if there is a M-sport? and wtf is "modern"?
I think overall its a crap idea and they should have kept it the way it was before. Let people spec their car how they want it. Give them more options if you want, like the different colours for the dash and steering wheels and M-sport package, but get rid of these stupid lines!