1. really all they did was remove the screaming, but they already had a lot of singing anyways
2. the rest of that album would fit in with this new song if he screamed maybe a few lines
3. they only got rid of a guitarist (and didn't replace him) since they have been signed
4. musically its not to different
All of these things. It is interesting though because at first they do appear to be really different styles. He's changed up his singing stylistically and it's mixed/mastered a little more evenly instead of the aggressive rhythm section, but yea, very similar.