It looks like the same designer to me but the scans of the article with Ayumi doesn't say who designed it (that info is probably in the back of the magazine and not part of the feature).

Ayumi looks like she's wearing a bodice/corset under her dress. But (totally OT) I think it looks better on Paris because the dress is made for someone with her figure and height. If Ayumi stood up in those photos, you'd see that the dress is much too long for her.