The blue is more dense and has a slightly higher R factor for the same thickness insulation wise. Occasionally it is more expensive than the pink.
As far as carving goes, anything done in blue seems to be harsh in the edges like it was too hard to work and the pink seems to blend and form with a heat gun more uniformly.
On the same token the blue might not be as delicate to abuse, handling and storage knocks and dings.
Another fabulous post from the U.S.Department of Wild Imaginings, now in spectaclar stereo, sponsored by the Adhesives and Sealants Council, suggesting ways to stick things together since the 1800s. Not fabulous in a gay way. Your results may vary. Illinois residents add 8% sales tax. These posts have been made by professional post makers, do not try this type of posting on your own without extensive training, lovely assistants and a trusty clown horn.