A Hat For a Boy or Yarn Is A Funny Thing

I knit this watch cap for my guy as a Christmas gift. Well, I knit this pattern. the gift cap was navy blue and worked in Cascade 220. He loves it and looks surprisingly smashing it so he wanted another in a second colour. He requested gray to match his good overcoat.

This charcoal gray version is also Cascade 220. Here's the funny thing. You'll notice the gray is slightly heathered? Well the short white fibers used to create the heathering differ from the main wool. They are coarser and slightly straighter. Consequently, the yarn of this cap behaves entirely differently from the first, navy blue, version. It is spongier, less springy. The finished product feels thicker. Both hats are very nice but isn't it remarkable that the addition of one small element makes them seem as if they were knit from completely different yarns?