I think that Cap has a beard now since he's been in hiding, so to speak, after the events of Civil War.
His arms appear to still be there, but equipped with individual shields, which I think will be an interesting upgrade from his traditional shield!
I did notice that Thanos is noticeably less intimidating. He has a more pink color, which, in addition to his seemingly shortened height, makes him seem less of a threat then when he was menacingly purple and sitting on his giant space throne.
Overall, I'm SUPER excited for this! Seeing all of the cast will be amazing!