Hello,
The blueish-gray substance is called lichen.  These are made up of a fungus and an algae (or sometimes a bacteria, or both) living in a symbiotic relationship.  This means they help each other but do not do any harm to the tree.  Here is an article that explains more about lichens.  https://extension.umd.edu/resource/lichen-algae-and-moss-trees/
The brown growth is a fungus that appears to be a brown toothed crust fungus.  This fungus is found on already dead trees and branches, because rotting wood is its food source.  This source shows some more pictures of the fungus, but does not tell you much about it: https://www.marylandbiodiversity.com/view/10229
I hope this is helpful.
Thank you for contacting Ask Extension.
Ruth