I don't think the comparison is valid.
I believe I-Novae are going for Milky Way numbers of stars, ie about 300 billion (3x1011). The Andromeda galaxy has over 3 times more at 1 trillion (1012) stars.
In addition, that photo will include many stars in the Milky Way between us and Andromeda (obviously including the big brighter ones).
Also, the model does not include dust which I think does a lot of reflecting and refracting and I imagine has a significant affect on the observed brightness of the image.
Finally, if your perspective was more like the Infinity video (ie inside the Andromeda galaxy looking outwards), I expect your view would be far more similar.
I'm sure @Kichae will correct me if I am wrong and will be able to educate beyond my assumptions.