Looks like a freeze out to me. I’ve seen this over and over in my mating nucs before giving them more insulation.
In a perfect world, the bees will consume honey, generate heat and keep themselves alive. However if something goes amiss and they don’t generate the heat they need, they will get too cold and die; that much is certain.
The heat generating machine can fail if a sudden arctic blast catches the bees out of cluster, or if they run out of stores inside the cluster, or if the cluster is too small, or etc. The bees on the outer periphery of the cluster act like insulators when in cluster. If that layer of insulation is insufficient, they're going to loose too much heat and freeze to death.
Your second photo is not showing up on my computer, but the first one really doesn't have very many bees.