Shion is taller, but not this much taller. Based on their AoCF sprites no, Shion is not this much taller than Jo'on. Although, Shion is barefoot while Jo'on has boots, so without her boots, Jo'on might be around her height in this picture, compared to Shion. Shion seems to be wearing the boots here though, so that could be the reason why she's so much taller.
