Actually, even before the novelizations came out, full synopses of both movies, along with scripts written for season two, were published in the book "Newcomers Among Us," an Alien Nation companion; and a comic book version of "Soul Train," which would have been the second season premiere, was released. So for me it gave the actual aired "Dark Horizon" movie a richer history; it was interesting to see how the story morphed from "Soul Train" to the original "Dark Horizon" script to the novel to the final movie.
The original "Body and Soul" was a lot different, actually a lot bigger story, and elements of the original eventually fed three different Alien Nation movies. The story of the boy taking advantage of Emily in "Millennium" came from the original "Body and Soul" script, as did the story of Albert and May asking George to help the two have a baby which, I think, ended up in "The Enemy Within." Because the X-Files was a big hit at the time, Fox asked Kenneth Johnson to add lots of government conspiracy stuff to the script.