That is a good looking plant.
I have a ~26" iMac with HD display. It is not that I cannot see the image properly, I am just completely convinced, the more I look at the lower level of the spines on that plant, that it is a Ferocactus. I have already stated I do not think it is F. chrysacanthus, but unless we can see young new growth the picture in question does not allow us to determine that with certainty.
The poster, if he responds, will likely argue that the label states it is F. chrysacanthus and that is why he posted it here in the database. I cannot fault him for that, despite my doubt about the proper ID, and the fact that even at the best Botanical Garden institutions mistakes get made or the occasional mis-identified plant gets added to the collection. However until we have evidence that without a doubt shows it is not F. chrysacanthus this photo either stays here or at most gets moved to the Ferocactus sp. entry. I would be fine with that as I do doubt the ID, but not that it is a Ferocactus.
And am I sorry, because I hate to be the guy who has to say that your personal observations and conditions do not count, but unfortunately in this case your summer/winter variation example is nothing like taking a plant grown for most of its early life, possibly as long as 15-20 years in say a southern California desert nursery or actually on Cedros island and then moving it to a green house environment somewhere else completely, implying that the conditions outside would not be suitable for the survival of that plant. So it goes into a possibly much cooler, likely more humid and less sunny environment on top of the fact that it is in a green house where a lot of any remaining harshness of the sun is blocked out. I do know how long the plant spent in that environment but given its size probably at least another 10-15 years if not more.
In these kind of conditions spine development will not favor the characteristic thick flat central spines we are so used to seeing on Ferocacti and radial spines may be minimally or not at all present, giving the cactus a very different look. However, absent an obvious graft, this plant did not go from being a Ferocactus in its early years to something completely different later, the conditions just affected its spine growth and it did not just experience a season of major change in conditions it experienced many years of it after having had very different conditions for many years before that. Most cacti take a good chunk of time to get past an experience like that and in some cases they never do, looking like a diminished version of themselves for the rest of their lives or until they get better conditions.
Something comparable but the opposite and much more extreme would be you sending me that Ferocactus you posted a picture of and me putting it out in the full sun in the summer in my front yard. It would be shocked so baldly it would probably be dead in a couple of weeks, but if it did survive in a few years there is a pretty good chance you would have a hard time recognizing it.
