This is a very beautiful and fascinating APOD, but the colors of the Small Magellanic Cloud and 47 Tuc confuse me.
The Small Magellanic Cloud is a blue galaxy. Its B-V, according to my software, is +0.45. 47 Tuc, on the other hand, is red as globulars go. Its B-V, according to Sky Catalogue 2000.0 part 2, is +0.89. So the Small Magellanic Cloud is clearly bluer than 47 Tuc, as can be seen here
in a picture from Capella Observatory. The reason for the red color of 47 Tuc is that although this globular is much more metal-poor than the Sun, it is still metal-rich for a globular. Its [Fe/H] value is -0.71, again according to Sky Catalogue, while a typical "blue globular" like M13 in Hercules has a [Fe/H] value of -1.65.
The relatively metal-rich nature of 47 Tuc means that this globular has no blue horizontal stars. This diagram from aanda.org
shows a short little "wing" stretching to the left about midway up the diagram. The "wing" is a red horizontal branch. It's red, because the bluest stars here are no bluer than the Sun, and the reddest stars on this "wing" are considerably redder. Compare the red horizontal branch of 47 Tuc with a blue horizontal branch
in a more metal-poor globular cluster. The blue horizontal branch is in the upper left of this diagram.
So 47 Tuc actually contains no blue stars, apart from relatively faint blue stragglers and extremely faint white dwarfs. But in today's APOD, a swarm of blue stars seem to form a halo around 47 Tuc. By contrast, blue galaxy SMC, which is full of young blue stars, seems to contain a large number of red stars. It does, of course. Interestingly, the SMC is quite metal-poor as galaxies go, and it would be fascinating if it had about the same metallicity as 47 Tuc. Indeed, according to The Galaxies of the Local Group
(2000) by Sidney van den Bergh, young clusters in the SMC has a [Fe/H] value of +0.74, almost exactly the same as 47 Tuc! An interesting aspect of metal-poor galaxies is that they contain a disproportionate number of very red carbon stars (or rather, low-luminosity galaxies in the Local Group contain disproportionate numbers of red carbon stars, according to Sidney van den Bergh). In any case, the SMC has a lot of carbon stars, and some of the very red stars in today's APOD may be such carbon stars.
I'm trying to say that I would have expected the SMC to look bluer than 47 Tuc, but it doesn't in this image. Of course, we only see a rather small part of the SMC, which may not be typical of the overall color of this galaxy. In any case, this is certainly very fascinating and beautiful APOD!