Like wax, shatter can come in multiple consistencies. The sappier, gooier variety is run with decarboxylated (activated) THC, which is in oil form at room temperature. Sappier shatter can also have more CBDs and terpenes than the brittle stuff, making for a better smell and taste if purged correctly.
Shatter Nugs are made entirely from cannabis flowers rather than trim material. Since the flowers are the most trichome and terpene-rich part of the cannabis plant, these extracts are known for yielding quite a bit more than trim as well as providing a cleaner flavor.