What the alternate ending does do is add one more callback to Kate and Tom’s conversations and how they impacted Kate’s life, which gives fans of the movie a little more of an understanding of what happens to Kate after the events in the movie.
From this point on spoilers for the movie will abound, so don’t say I didn’t warn you.
If you wondered whether or not the alternate ending would totally take Last Christmas’ big twist ending and go in a different direction, much of the way the movie ends is left intact.