The definition of a bully (from a dictionary)

A blustering, quarrelsome, overbearing person, who habitually badgers and intimidates smaller or weaker people.

Ironically these two traits “blustering quarrelsome and overbearing” – “habitually badgers and intimidates” are linked.

The bully suffers from internal shame, hence, externally he creates a mask, hence, “blustering quarrelsome and overbearing,” but internally, is jealous of people who are feeling good about themselves; hence the desire of jealousy is to make others feel shame; in that way (of course this is subconscious, for consciously he justifies his anger that “others are evil,” while he is!) so in this way, he feels less shame.