Hoya australis ssp. tenuipes 'Lisa' is a completely different plant from Hoya tricolor (which carries the proper names of either Hoya carnosa 'Krimson Queen' or Hoya carnosa tricolor). Hoya australis 'Lisa' has completely different flowers and leaves from the carnosas.

Your's is actually neither. Hoya carnosa Krimson Queen is an albomarginated plant (meaning the leaf edges are white, and the center of the leaves are green). Yours is a variegated plant (leaf edges are green and center of leaf is white), which means you have Hoya carnosa Krimson Princess a.k.a Hoya carnosa 'Rubra' or Hoya carnosa variegated.

An easy way to remember whether or not you have Krimson Queen or Krimson Princess:

The Queen wears her white like a crown (the leaf edges are white, like a silver crown)

The Princess wears her white like a gown (the white is in the middle of the leaf; leaf edges/margins are green).

For a comparison, here is my australis 'Lisa':

And my Hoya carnosa 'Krimson Queen':

Thank you so much for the clarification! And the info provided. I was confused with what appears on the net.
Actually, I contacted the person from where I obtained the cutting(s) and said that the buyer from where that person bought the plant, it was sold as Hoya australis 'Tricolor'. The image below shows the plant that was sold from the initial buyer, as H. australis 'Tricolor':

So, I am trying to locate the differences between the two (H. australis 'Tricolor'/H. carnosa 'Rubra') by looking the first image. It would be much easier for me if I had the two plants side by side. I guess the difference in the leaves is to be found at the size? Those of australis must be larger, right? Are there any other differences in the leaves?

No. There is no such thing as Hoya australis 'Tricolor'.

There are MANY differences in the leaves AND flowers of Hoya australis 'Lisa' and Hoya carnosa.

The photos that were sent to you are that of Hoya carnosa. Not Hoya australis (of any type). Here are a few bloom photos of Hoya carnosa, courtesy of AHHoya:

Hoya australis has pretty much the same type of flowers, no matter whar cultivar, sub-species, whatever, and they look nothing like carnosa.

Here are three different species of australis flowers. Note that they look nothing like carnosa's blooms. Bloom photo credit to AHHoya:

Note how much they look alike.

As far as leaf differences go, Hoya carnosa has thick, succulent leaves, whereas Hoya australis 'Lisa' has thin leaves. The leaf shape and mature vine color, and peduncle color are also totally different between the species. Compare the look of my Australis 'Lisa' to that of your carnosa Krimson Princess: