The m.nzx.com site looks as though it maybe more specific to viewing on mobile devices such as phones and tablets (hence the m) and it is having just tried it, plus as PT says the "old" site is still right up to date
My very limited knowledge of website construction, seems to tell me these days that most new/upgraded sites automatically detect what kind of device you are viewing on and adjust it accordingly.
No sign of this with nzx.com as yet, though that site was down for awhile at least and the m.nzx.com site was working - progress still in the works maybe