I honestly don't think Snyder had thought much about his plans for Wonder Woman. Going off of interviews and how she was written in BvS I think she was more of an after thought for him.
Not much of a difference, really. It was more about their more optimistic tone necessitating that final voice over in Wonder Woman making it clear that she would never give up on humanity. Presumably, the original version would have seen her remain in Man's World, helping out in secret, but her initial naive faith in humanity's goodness was now more realistic thanks to her experiences with Steve.
Again, not a huge change, but a necessary one to make, which required Justice League to reconcile the two different notions of her from BvS and WW.
"You're a beacon to the world. And yet, I'd never heard of you until Luthor drew you out of hiding with a picture of your dead boyfriend." ~ Bruce Wayne, "Justice League"
If Batman has never heard of you, that means you walked away & were in hiding. Gadot can say whatever she wants in interviews, but on-screen nothing has been retconned yet. WW 2 may change that, but so far the BvS ending is still the canon one.
"Darkseid...always hated music..."
Every post I make, it should be assumed by the reader that the following statement is attached: "It's all subjective. What works for me doesn't necessarily work for you, and vice versa, and that's ok. You may have a different opinion on it, but this is mine. That's the wonderful thing about being a comics fan, it's all subjective."
Wonder Woman had been in production hell for generations, but the most recent production originally was slated to have Michelle MacLaren as director. She walked away over creative differences and we know that the script was revised by a few different people. I imagine the script was close to its final form when Snyder filmed BVS since they shot the photograph scene for WONDER WOMAN to fit in with BVS (and Snyder was on set for that).
But I think the final edit of WONDER WOMAN downplays her leaving humanity. You could argue that a hundred years ago she did walk away from humanity--in the scene where she tells Steve Trevor off--immediatlely after that she battles Ares and gets her faith back. But for those few minutes of screen time she had walked away from humanity and that was a hundred years ago.
In JUSTICE LEAGUE, Batman doesn't seem to have watched the WONDER WOMAN movie, even though Diana emailed him the whole story, as Bruce holds it against her that she walked away from humanity--and in his version of the story, she never got back to helping mankind until their battle with Doomsday. So Snyder seems to have stuck with the original idea from BVS that was probably in an earlier draft of WW. And Joss Whedon never changed that in the final cut--which is something you'd think he would have changed to make JL more cheery.
However, from what Gal Gadot has said in interviews and from what we know about Patty Jenkins plans for the next movie--that idea is either going to be dropped or downplayed.
Anyway, I think future DC movies as a whole are going to do a soft reboot on any continuity from the Snyder movies.