In the Sansa-Bran hug, Bran’s hands never lift up to hug Sansa.
In the first Sansa-Arya hug, Sansa hugs Arya, but Arya’s hands remain at her side.
In the second Sansa-Arya hug, Arya has warmed up a little (recapturing another small piece of her humanity) and she hugs back.
When Arya hugs Bran, Bran’s hand comes up to hug her back. Considering how unfeeling Bran is at this point, I think this shows a lot more about the kids’ original relationships when they were growing up.
Sansa was a stuck up, dishonest, and sometimes cruel teenager, while Arya and Bran were playmates who may have fought with each other, but probably had the deepest connection with each other. (Rickon was the baby who got in the way, and the rest of the Stark children were teenagers who, in the real world, would want nothing to do with their younger siblings, except for Jon Snow, who knew how it felt to be left out and seemed to have a speical bond with both Arya and Bran.)
I think it’s possible that Winterfell will break down into two camps: Jon Snow-Arya-Bran vs Sansa-Littlefinger.