Main difference: Justin's lyrics no longer touch on the everyday life we all live.
Look at "Dog And Wolf." The lyrics are about broad topics, create feelings, go for imagery, ambiguity, bigger canvas... Take the title track, "Knievel," "Horsemen"....do they speak about our everyday life, people we know?
Now compare to the classic NMA lineup and what they were covering lyrically. "Better Than Them," "Smalltown England," "Frightened," "I Wish," "Notice Me," "Great Expectations," "Young Gifted and Skint"....the lyrics were about ourselves and people we know! That was part of the attraction to the band. Justin's lyrics were about our lives and how we lived them. The characters in his songs I knew. Maybe we were one of the characters in those songs. No better example is "Better Than Them." That song is so real in depicting how we live.
That's not the case anymore. He has shifted his lyrics to more esoteric stuff. I miss the stuff about us and our lives.