Different skin, hair and facial structure. More like the voice access (who's name sadly escapes me right now) that played her but it's a little tenuous to call TLoU 2 from a possible random coincidence to be fair.
I'm going to assume we need to spoiler things here.
did you play the game all the way through? Ellie has a benign form of the fungus that will never progress to full on infection like everyone else. They could have taken it out of her and used it to vaccinate everyone, but this would have killed her. She should live an otherwise normal life that an uninfected person would.