Never been down there!
Sorry to say, I've never visited Australia or New Zealand so I don't know what you've got for navaids.
But in the US we've got:
TACAN (TACtical Air Navigation)...military
VOR (Very high freq Omnirange Radio)
VORTAC (VOR with TACAN)
VOR/DME (VOR with DME)
I'm keeping it real basic for the neophytes.
TACAN provides range (DME) and azimuth (course) on UHF.
VOR provides azimuth only. (VHF)
But a VORTAC (a VOR station co-located with a TACAN station) serves two masters: civilian and military.
Civilian guys get their azimuth from the VOR portion.
Military guys get their azimuth from the TACAN portion.
But *both* get their DME from the TACAN on UHF.
Since civilian guys don't have UHF equipment the UHF DME freq must be "paired" with a usable VHF freq....and it's real convenient that they use the same freq as the VOR.
And of course a VOR/DME is just a VOR station co-located with a DME station so effectively it operates the same as a VORTAC for a civilian operator but there's no TACAN available for military.
It's a little bit of mix and match but it works well. I hope that helps answer your question.